API Client Initialization Fails with "fetch failed" Error During RPC Calls

[Shogunnn22]

I'm experiencing intermittent failures during Polkadot API client initialization in my App. The initialization process fails with "fetch failed" errors when making RPC calls like getRuntimeVersion or getBlockHash.

Environment

• @polkadot/api version: 14.3.1
• Node.js version: 18
• Network: Polkadot (relay chain)

Code

const { ApiPromise, HttpProvider } = require("@polkadot/api");

~~~

class PolkadotApi {

    static create = async (config) => {
        const httpProvider = new HttpProvider(config.nodeUrl);
        config.api = await ApiPromise.create({ provider: httpProvider });
        return new PolkadotApi(config);
    }

~~~

Error Details

pattern1

WARN	2025-06-16 04:39:01        API/INIT: Api will be available in a limited mode since the provider does not support subscriptions
ERROR	2025-06-16 04:39:01        RPC-CORE: getRuntimeVersion(at?: BlockHash): RuntimeVersion:: fetch failed
ERROR	2025-06-16 04:39:01        API/INIT: Error: FATAL: Unable to initialize the API: fetch failed
    at ApiPromise.__internal__onProviderConnect (/var/task/node_modules/@polkadot/api/cjs/base/Init.js:386:27)

pattern2

WARN	2025-06-15 20:56:40        API/INIT: Api will be available in a limited mode since the provider does not support subscriptions
ERROR	2025-06-15 20:56:40        RPC-CORE: getRuntimeVersion(at?: BlockHash): RuntimeVersion:: fetch failed
ERROR	2025-06-15 20:56:40        API/INIT: Error: FATAL: Unable to initialize the API: fetch failed
    at ApiPromise.__internal__onProviderConnect (/var/task/node_modules/@polkadot/api/cjs/base/Init.js:386:27)
ERROR	2025-06-15 20:56:40        RPC-CORE: getBlockHash(blockNumber?: BlockNumber): BlockHash:: fetch failed
ERROR	2025-06-15 20:56:40        RPC-CORE: properties(): ChainProperties:: fetch failed
ERROR	2025-06-15 20:56:40        RPC-CORE: methods(): RpcMethods:: fetch failed
ERROR	2025-06-15 20:56:40        RPC-CORE: chain(): Text:: fetch failed

What Investigated

✅ Block integrity: The specific blocks being processed appear to be valid
✅ Infrastructure resources: Currency node instances show normal memory and disk usage
❌ Root cause: Still investigating the underlying network/RPC issue

Expected Behavior

API client should initialize successfully and be ready to process blockchain data.

Actual Behavior

Initialization fails with "fetch failed" errors, causing abnormal termination of the BlockHandler process.

Questions

• Are there known issues with RPC call reliability during API initialization?
• Should we implement retry logic specifically for initialization phase?
• Are there recommended timeout or connection pool settings for serverless environments?
• Could this be related to WebSocket connection handling in Lambda environments?
• This appears to be an intermittent issue rather than a consistent failure, suggesting potential network connectivity or timing-related causes. Any recommendations on production-ready error handling patterns for @polkadot/api in serverless architectures would be greatly appreciated.

[valentinfernandez1]

Two questions before going any further. Which Polkadot RPC are you connecting to? It's possible that the node is unstable and that is why you get intermittent errors.

Additionally could you add this before starting your application?

export export DEBUG=api-ws

This will enable the api to log all the WebSocket requests. Once the error appears please submit the logs so that we can take a better look at what is going on.

Side note:
The API may fail to initialize if there is a problem with the node that is trying to connect to. If you want extra reliability you might want to have a list of RPCs and switch the Rpc if one fails to connect.

[Shogunnn22]

Thank you for the quick response and suggestions!

I'm connecting to my own self-hosted Polkadot node with the following configuration:

--rpc-external
--chain=polkadot
--database=rocksdb
--state-pruning=1000
--blocks-pruning=150000
--rpc-port=9933
--sync=fast
--rpc-cors=all
--detailed-log-output
--log=info

Are there any specific node configuration parameters you'd recommend for better RPC stability, especially for production workloads?

I'll add export DEBUG=api-ws to enable WebSocket request logging and capture the logs when the error occurs next.
However, since I cannot stop my production service, implementing this option might be challenging, but I'll try to find a way to enable it safely.

[milc0x]

@valentinfernandez1

I’ve reproduced the issue with DEBUG=api-ws enabled.
I’m using @polkadot/api v14.3.1 and connecting to the public endpoint at wss://rpc.polkadot.io.

Here are the relevant logs:
①

2025-07-08 04:05:40          API-WS: connected to wss://rpc.polkadot.io
2025-07-08 04:05:40          API-WS: calling chain_getBlockHash {"id":1,"jsonrpc":"2.0","method":"chain_getBlockHash","params":[0]}
2025-07-08 04:05:40          API-WS: calling state_getRuntimeVersion {"id":2,"jsonrpc":"2.0","method":"state_getRuntimeVersion","params":[]}
2025-07-08 04:05:40          API-WS: calling system_chain {"id":3,"jsonrpc":"2.0","method":"system_chain","params":[]}
2025-07-08 04:05:40          API-WS: calling system_properties {"id":4,"jsonrpc":"2.0","method":"system_properties","params":[]}
2025-07-08 04:05:40          API-WS: calling rpc_methods {"id":5,"jsonrpc":"2.0","method":"rpc_methods","params":[]}
2025-07-08 04:23:24        RPC-CORE: getBlockHash(blockNumber?: BlockNumber): BlockHash:: No response received from RPC endpoint in 60s
2025-07-08 04:23:24        RPC-CORE: getRuntimeVersion(at?: BlockHash): RuntimeVersion:: No response received from RPC endpoint in 60s
2025-07-08 04:23:24        RPC-CORE: chain(): Text:: No response received from RPC endpoint in 60s
2025-07-08 04:23:24        RPC-CORE: properties(): ChainProperties:: No response received from RPC endpoint in 60s
2025-07-08 04:23:24        RPC-CORE: methods(): RpcMethods:: No response received from RPC endpoint in 60s
2025-07-08 04:23:24        API/INIT: Error: FATAL: Unable to initialize the API: No response received from RPC endpoint in 60s
    at ApiPromise.__internal__onProviderConnect (/Users/polkadot-api-debug/node_modules/@polkadot/api/cjs/base/Init.js:386:27)
    at runNextTicks (node:internal/process/task_queues:60:5)
    at process.processTimers (node:internal/timers:509:9)

②

2025-07-08 04:23:55          API-WS: connected to wss://rpc.polkadot.io
2025-07-08 04:23:55          API-WS: calling chain_getBlockHash {"id":1,"jsonrpc":"2.0","method":"chain_getBlockHash","params":[0]}
2025-07-08 04:23:55          API-WS: calling state_getRuntimeVersion {"id":2,"jsonrpc":"2.0","method":"state_getRuntimeVersion","params":[]}
2025-07-08 04:23:55          API-WS: calling system_chain {"id":3,"jsonrpc":"2.0","method":"system_chain","params":[]}
2025-07-08 04:23:55          API-WS: calling system_properties {"id":4,"jsonrpc":"2.0","method":"system_properties","params":[]}
2025-07-08 04:23:55          API-WS: calling rpc_methods {"id":5,"jsonrpc":"2.0","method":"rpc_methods","params":[]}
2025-07-08 04:23:55          API-WS: received {"jsonrpc":"2.0","id":1,"result":"0x91b171bb158e2d3848fa23a9f1c25182fb8e20313b2c1eb49219da7a70ce90c3"}
2025-07-08 04:23:55          API-WS: received {"jsonrpc":"2.0","id":5,"result":{"methods":["account_nextIndex","archive_v1_body","archive_v1_call","archive_v1_finalizedHeight","archive_v1_genesisHash","archive_v1_hashByHeight","archive_v1_header","archive_v1_stopStorage","archive_v1_storage","archive_v1_storageDiff","archive_v1_storageDiff_stopStorageDiff","author_hasKey","author_hasSessionKeys","author_insertKey","author_pendingExtrinsics","author_removeExtrinsic","author_rotateKeys","author_submitAndWatchExtrinsic","author_submitExtrinsic","author_unwatchExtrinsic","babe_epochAuthorship","beefy_getFinalizedHead","beefy_subscribeJustifications","beefy_unsubscribeJustifications","chainHead_v1_body","chainHead_v1_call","chainHead_v1_continue","chainHead_v1_follow","chainHead_v1_header","chainHead_v1_stopOperation","chainHead_v1_storage","chainHead_v1_unfollow","chainHead_v1_unpin","chainSpec_v1_chainName","chainSpec_v1_genesisHash","chainSpec_v1_properties","chain_getBlock","chain_getBlockHash","chain_getFinalisedHead","chain_getFinalizedHead","chain_getHead","chain_getHeader","chain_getRuntimeVersion","chain_subscribeAllHeads","chain_subscribeFinalisedHeads","chain_subscribeFinalizedHeads","chain_subscribeNewHead","chain_subscribeNewHeads","chain_subscribeRuntimeVersion","chain_unsubscribeAllHeads","chain_unsubscribeFinalisedHeads","chain_unsubscribeFinalizedHeads","chain_unsubscribeNewHead","chain_unsubscribeNewHeads","chain_unsubscribeRuntimeVersion","childstate_getKeys","childstate_getKeysPaged","childstate_getKeysPagedAt","childstate_getStorage","childstate_getStorageEntries","childstate_getStorageHash","childstate_getStorageSize","grandpa_proveFinality","grandpa_roundState","grandpa_subscribeJustifications","grandpa_unsubscribeJustifications","mmr_generateProof","mmr_root","mmr_verifyProof","mmr_verifyProofStateless","offchain_localStorageClear","offchain_localStorageGet","offchain_localStorageSet","payment_queryFeeDetails","payment_queryInfo","rpc_methods","state_call","state_callAt","state_getChildReadProof","state_getKeys","state_getKeysPaged","state_getKeysPagedAt","state_getMetadata","state_getPairs","state_getReadProof","state_getRuntimeVersion","state_getStorage","state_getStorageAt","state_getStorageHash","state_getStorageHashAt","state_getStorageSize","state_getStorageSizeAt","state_queryStorage","state_queryStorageAt","state_subscribeRuntimeVersion","state_subscribeStorage","state_traceBlock","state_trieMigrationStatus","state_unsubscribeRuntimeVersion","state_unsubscribeStorage","subscribe_newHead","sync_state_genSyncSpec","system_accountNextIndex","system_addLogFilter","system_addReservedPeer","system_chain","system_chainType","system_dryRun","system_dryRunAt","system_health","system_localListenAddresses","system_localPeerId","system_name","system_nodeRoles","system_peers","system_properties","system_removeReservedPeer","system_reservedPeers","system_resetLogFilter","system_syncState","system_unstable_networkState","system_version","transactionWatch_v1_submitAndWatch","transactionWatch_v1_unwatch","transaction_v1_broadcast","transaction_v1_stop","unsubscribe_newHead"]}}
2025-07-08 04:23:55          API-WS: received {"jsonrpc":"2.0","id":4,"result":{"ss58Format":0,"tokenDecimals":10,"tokenSymbol":"DOT"}}
2025-07-08 04:23:55          API-WS: received {"jsonrpc":"2.0","id":2,"result":{"specName":"polkadot","implName":"parity-polkadot","authoringVersion":0,"specVersion":1005001,"implVersion":0,"apis":[["0xc51ff1fa3f5d0cca",1],["0xdf6acb689907609b",5],["0x37e397fc7c91f5e4",2],["0x40fe3ad401f8959a",6],["0x17a6bc0d0062aeb3",1],["0x18ef58a3b67ba770",1],["0xd2bc9897eed08f15",3],["0xf78b278be53f454c",2],["0xaf2c0297a23e6d3d",12],["0x49eaaf1b548a0cb0",5],["0x91d5df18b0d2cf58",2],["0x2a5e924655399e60",1],["0xed99c5acb25eedf5",3],["0xcbca25e39f142387",2],["0x687ad44ad37f03c2",1],["0xab3c0572291feb8b",1],["0xbc9d89904f5b923f",1],["0x37c8bb1350a9a2a8",4],["0xf3ff14d5ab527059",3],["0x6ff52ee858e6c5bd",1],["0x91b1c8b16328eb92",2],["0x9ffb505aa738d69c",1],["0xfbc577b9d747efd6",1]],"transactionVersion":26,"systemVersion":1,"stateVersion":1}}
2025-07-08 04:23:55          API-WS: received {"jsonrpc":"2.0","id":3,"result":"Polkadot"}
2025-07-08 04:23:55          API-WS: calling state_call {"id":6,"jsonrpc":"2.0","method":"state_call","params":["Metadata_metadata_versions","0x"]}
2025-07-08 04:23:55          API-WS: received {"jsonrpc":"2.0","id":6,"result":"0x0c0e0000000f000000ffffffff"}
2025-07-08 04:23:55          API-WS: calling state_getMetadata {"id":7,"jsonrpc":"2.0","method":"state_getMetadata","params":[]}
2025-07-08 04:40:20        RPC-CORE: getMetadata(at?: BlockHash): Metadata:: No response received from RPC endpoint in 60s
2025-07-08 04:40:20        API/INIT: Error: FATAL: Unable to initialize the API: No response received from RPC endpoint in 60s
    at ApiPromise.__internal__onProviderConnect (/Users/polkadot-api-debug/node_modules/@polkadot/api/cjs/base/Init.js:386:27)
    at runNextTicks (node:internal/process/task_queues:60:5)
    at process.processTimers (node:internal/timers:509:9)

③

2025-07-08 06:04:52          API-WS: connected to wss://rpc.polkadot.io
2025-07-08 06:04:52          API-WS: calling state_subscribeRuntimeVersion {"id":20,"jsonrpc":"2.0","method":"state_subscribeRuntimeVersion","params":[]}
2025-07-08 06:04:52          API-WS: received {"jsonrpc":"2.0","id":9,"result":"Polkadot"}
[2025-07-07T21:04:52.948Z] Connected to chain: Polkadot
2025-07-08 06:04:52          API-WS: calling chain_getHeader {"id":10,"jsonrpc":"2.0","method":"chain_getHeader","params":[]}
2025-07-08 06:04:52          API-WS: received {"jsonrpc":"2.0","id":20,"result":"VdRRGYthJwISRauF"}
2025-07-08 06:04:52          API-WS: received {"jsonrpc":"2.0","method":"state_runtimeVersion","params":{"subscription":"VdRRGYthJwISRauF","result":{"specName":"polkadot","implName":"parity-polkadot","authoringVersion":0,"specVersion":1005001,"implVersion":0,"apis":[["0xc51ff1fa3f5d0cca",1],["0xdf6acb689907609b",5],["0x37e397fc7c91f5e4",2],["0x40fe3ad401f8959a",6],["0x17a6bc0d0062aeb3",1],["0x18ef58a3b67ba770",1],["0xd2bc9897eed08f15",3],["0xf78b278be53f454c",2],["0xaf2c0297a23e6d3d",12],["0x49eaaf1b548a0cb0",5],["0x91d5df18b0d2cf58",2],["0x2a5e924655399e60",1],["0xed99c5acb25eedf5",3],["0xcbca25e39f142387",2],["0x687ad44ad37f03c2",1],["0xab3c0572291feb8b",1],["0xbc9d89904f5b923f",1],["0x37c8bb1350a9a2a8",4],["0xf3ff14d5ab527059",3],["0x6ff52ee858e6c5bd",1],["0x91b1c8b16328eb92",2],["0x9ffb505aa738d69c",1],["0xfbc577b9d747efd6",1]],"transactionVersion":26,"systemVersion":1,"stateVersion":1}}}
2025-07-08 06:04:53          API-WS: received {"jsonrpc":"2.0","id":20,"result":"RcLizn9UbAVdfQpe"}
2025-07-08 06:04:53          API-WS: received {"jsonrpc":"2.0","method":"state_runtimeVersion","params":{"subscription":"RcLizn9UbAVdfQpe","result":{"specName":"polkadot","implName":"parity-polkadot","authoringVersion":0,"specVersion":1005001,"implVersion":0,"apis":[["0xc51ff1fa3f5d0cca",1],["0xdf6acb689907609b",5],["0x37e397fc7c91f5e4",2],["0x40fe3ad401f8959a",6],["0x17a6bc0d0062aeb3",1],["0x18ef58a3b67ba770",1],["0xd2bc9897eed08f15",3],["0xf78b278be53f454c",2],["0xaf2c0297a23e6d3d",12],["0x49eaaf1b548a0cb0",5],["0x91d5df18b0d2cf58",2],["0x2a5e924655399e60",1],["0xed99c5acb25eedf5",3],["0xcbca25e39f142387",2],["0x687ad44ad37f03c2",1],["0xab3c0572291feb8b",1],["0xbc9d89904f5b923f",1],["0x37c8bb1350a9a2a8",4],["0xf3ff14d5ab527059",3],["0x6ff52ee858e6c5bd",1],["0x91b1c8b16328eb92",2],["0x9ffb505aa738d69c",1],["0xfbc577b9d747efd6",1]],"transactionVersion":26,"systemVersion":1,"stateVersion":1}}}
2025-07-08 06:04:53          API-WS: received {"jsonrpc":"2.0","id":10,"result":{"parentHash":"0x394fc705033bc9144e47ae1cc78993e109798780a15a5ff620e1c753cd456fdd","number":"0x198a185","stateRoot":"0x9aa3fc451eba4815af9c0f15aa79be92570d83c87c391540ea1eb271dedfa8fd","extrinsicsRoot":"0x31902befc0a9431ce54a6605cf740799ac80a40c0fe43aa7782324597ae09c15","digest":{"logs":["0x0642414245b50101db000000685e67110000000092259621bfc05b7fa020594498fad93deae11743e07592892d42d0708d977c34773efb989678971ee279c9449947246c04f40c2a70375bad74ee7a80858f6a0e95031fe0dd6e7c2fc9ed85755e2ff4dc54f360c98c0d53991997233c04fe5e05","0x04424545468403bcef6a9f3d846aac17b10f81d7297d9fc777c6557d3dd41dbb38932f5eb8b256","0x05424142450101e613ab0a9fab8a9c1f4089520cd3052c7fb8da830174df3e8624ec0a7644b252a71fa69964673d93f795645dc16b0d55c39d9e6958024592d405bf625f8ed688"]}}}
2025-07-08 06:04:53          API-WS: calling chain_getHeader {"id":11,"jsonrpc":"2.0","method":"chain_getHeader","params":["0x60fc01d2f113780d8208adb2b7460b525d7a7713dfc80b7d7d344a06dae1fdbe"]}
2025-07-08 06:04:53          API-WS: received {"jsonrpc":"2.0","id":11,"result":{"parentHash":"0x394fc705033bc9144e47ae1cc78993e109798780a15a5ff620e1c753cd456fdd","number":"0x198a185","stateRoot":"0x9aa3fc451eba4815af9c0f15aa79be92570d83c87c391540ea1eb271dedfa8fd","extrinsicsRoot":"0x31902befc0a9431ce54a6605cf740799ac80a40c0fe43aa7782324597ae09c15","digest":{"logs":["0x0642414245b50101db000000685e67110000000092259621bfc05b7fa020594498fad93deae11743e07592892d42d0708d977c34773efb989678971ee279c9449947246c04f40c2a70375bad74ee7a80858f6a0e95031fe0dd6e7c2fc9ed85755e2ff4dc54f360c98c0d53991997233c04fe5e05","0x04424545468403bcef6a9f3d846aac17b10f81d7297d9fc777c6557d3dd41dbb38932f5eb8b256","0x05424142450101e613ab0a9fab8a9c1f4089520cd3052c7fb8da830174df3e8624ec0a7644b252a71fa69964673d93f795645dc16b0d55c39d9e6958024592d405bf625f8ed688"]}}}
2025-07-08 06:04:53          API-WS: calling state_getRuntimeVersion {"id":12,"jsonrpc":"2.0","method":"state_getRuntimeVersion","params":["0x394fc705033bc9144e47ae1cc78993e109798780a15a5ff620e1c753cd456fdd"]}
2025-07-08 06:06:33        RPC-CORE: getRuntimeVersion(at?: BlockHash): RuntimeVersion:: No response received from RPC endpoint in 60s
2025-07-08 06:06:33        RPC-CORE: getBlock(hash?: BlockHash): SignedBlock:: No response received from RPC endpoint in 60s
[2025-07-07T21:06:33.729Z] Error: Error: No response received from RPC endpoint in 60s
    at WsProvider.__internal__timeoutHandlers (/Users/polkadot-api-debug/node_modules/@polkadot/rpc-provider/cjs/ws/index.js:502:38)
    at Timeout._onTimeout (/Users/polkadot-api-debug/node_modules/@polkadot/rpc-provider/cjs/ws/index.js:180:65)
    at listOnTimeout (node:internal/timers:569:17)
    at process.processTimers (node:internal/timers:512:7)

It seems like the connection times out — the RPC calls start failing one by one with “No response received from RPC endpoint in 60s”.

[rajk93]

Hi @milc0x,
Could you please try using the updated version of @polkadot/api, specifically v16.4.1? Also, could you share the code snippet you're using that is causing the issue?

For reference, I tested the following snippet with v16.4.1 and did not encounter any issues:

import { ApiPromise, WsProvider } from "@polkadot/api";

const providerUrl = "wss://rpc.polkadot.io";

async function main() {
  const wsProvider = new WsProvider(providerUrl);
  const api = await ApiPromise.create({ provider: wsProvider });

  const chain = await api.rpc.system.chain();
  const node = await api.rpc.system.name();
  const version = await api.rpc.system.version();

  console.log(`Connected to ${chain} at node ${node} version ${version}`);
}

main().catch(console.error);

[milc0x]

@rajk93

The following snippet is my code used to debug this issue.
I introduced a retry mechanism: if the connection fails, it will automatically try again up to 3 times, waiting 2 seconds between each attempt.

const { ApiPromise, WsProvider } = require('@polkadot/api');

async function withRetry(fn, retries = 3, delay = 2000) {
  let lastErr;
  for (let i = 0; i < retries; i++) {
    try {
      return await fn();
    } catch (err) {
      lastErr = err;
      console.warn(`[${new Date().toISOString()}] Retry ${i + 1} failed:`, err);
      if (i < retries - 1) {
        await new Promise(res => setTimeout(res, delay));
      }
    }
  }
  throw lastErr;
}

async function main() {
  try {
    const wsProvider = new WsProvider('wss://rpc.polkadot.io');
    const api = await withRetry(() => ApiPromise.create({ provider: wsProvider }));

    const chain = await api.rpc.system.chain();
    const now = new Date().toISOString();
    console.log(`[${now}] Connected to chain: ${chain}`);

    // Lastest block
    const lastHeader = await api.rpc.chain.getHeader();
    const blockHash = lastHeader.hash.toHex();
    const blockNumber = lastHeader.number.toString();
    const block = await api.rpc.chain.getBlock(blockHash);
    console.log(`[${now}] Latest block number: #${blockNumber}`);
    console.log(`[${now}] Block hash: ${blockHash}`);
    console.log(`[${now}] Block author: ${lastHeader.author || 'N/A'}`);
    console.log(`[${now}] Block extrinsics count: ${block.block.extrinsics.length}`);

    await api.disconnect();
  } catch (err) {
    console.error(`[${new Date().toISOString()}] Error:`, err);
  }
}

main();
setInterval(main, 10000);

[milc0x]

Could you please try using the updated version of @polkadot/api, specifically v16.4.1? Also, could you share the code snippet you're using that is causing the issue?

Actually, I tried using a newer version of @polkadot/api, specifically v16.3.1, with the same code as above yesterday.

However, I still encountered the same issue.
(And some errors have never been seen in older version.)

①

2025-07-09 02:55:33          API-WS: connected to wss://rpc.polkadot.io
2025-07-09 02:55:33          API-WS: calling chain_getBlockHash {"id":1,"jsonrpc":"2.0","method":"chain_getBlockHash","params":[0]}
2025-07-09 02:55:33          API-WS: calling state_getRuntimeVersion {"id":2,"jsonrpc":"2.0","method":"state_getRuntimeVersion","params":[]}
2025-07-09 02:55:33          API-WS: calling system_chain {"id":3,"jsonrpc":"2.0","method":"system_chain","params":[]}
2025-07-09 02:55:33          API-WS: calling system_properties {"id":4,"jsonrpc":"2.0","method":"system_properties","params":[]}
2025-07-09 02:55:33          API-WS: calling rpc_methods {"id":5,"jsonrpc":"2.0","method":"rpc_methods","params":[]}
2025-07-09 03:12:57        RPC-CORE: getBlockHash(blockNumber?: BlockNumber): BlockHash:: No response received from RPC endpoint in 60s
2025-07-09 03:12:57        RPC-CORE: getRuntimeVersion(at?: BlockHash): RuntimeVersion:: No response received from RPC endpoint in 60s
2025-07-09 03:12:57        RPC-CORE: chain(): Text:: No response received from RPC endpoint in 60s
2025-07-09 03:12:57        RPC-CORE: properties(): ChainProperties:: No response received from RPC endpoint in 60s
2025-07-09 03:12:57        RPC-CORE: methods(): RpcMethods:: No response received from RPC endpoint in 60s
2025-07-09 03:12:57        API/INIT: Error: FATAL: Unable to initialize the API: No response received from RPC endpoint in 60s
    at #onProviderConnect (/Users/polkadot-api-debug/node_modules/@polkadot/api/cjs/base/Init.js:390:27)
    at runNextTicks (node:internal/process/task_queues:60:5)
    at process.processTimers (node:internal/timers:509:9)

②

2025-07-09 03:12:58          API-WS: connected to wss://rpc.polkadot.io
2025-07-09 03:12:58          API-WS: calling chain_getBlockHash {"id":1,"jsonrpc":"2.0","method":"chain_getBlockHash","params":[0]}
2025-07-09 03:12:58          API-WS: calling state_getRuntimeVersion {"id":2,"jsonrpc":"2.0","method":"state_getRuntimeVersion","params":[]}
2025-07-09 03:12:58          API-WS: calling system_chain {"id":3,"jsonrpc":"2.0","method":"system_chain","params":[]}
2025-07-09 03:12:58          API-WS: calling system_properties {"id":4,"jsonrpc":"2.0","method":"system_properties","params":[]}
2025-07-09 03:12:58          API-WS: calling rpc_methods {"id":5,"jsonrpc":"2.0","method":"rpc_methods","params":[]}
2025-07-09 03:12:58          API-WS: received {"jsonrpc":"2.0","id":3,"result":"Polkadot"}
2025-07-09 03:12:58          API-WS: received {"jsonrpc":"2.0","id":5,"result":{"methods":["account_nextIndex","archive_v1_body","archive_v1_call","archive_v1_finalizedHeight","archive_v1_genesisHash","archive_v1_hashByHeight","archive_v1_header","archive_v1_stopStorage","archive_v1_storage","archive_v1_storageDiff","archive_v1_storageDiff_stopStorageDiff","author_hasKey","author_hasSessionKeys","author_insertKey","author_pendingExtrinsics","author_removeExtrinsic","author_rotateKeys","author_submitAndWatchExtrinsic","author_submitExtrinsic","author_unwatchExtrinsic","babe_epochAuthorship","beefy_getFinalizedHead","beefy_subscribeJustifications","beefy_unsubscribeJustifications","chainHead_v1_body","chainHead_v1_call","chainHead_v1_continue","chainHead_v1_follow","chainHead_v1_header","chainHead_v1_stopOperation","chainHead_v1_storage","chainHead_v1_unfollow","chainHead_v1_unpin","chainSpec_v1_chainName","chainSpec_v1_genesisHash","chainSpec_v1_properties","chain_getBlock","chain_getBlockHash","chain_getFinalisedHead","chain_getFinalizedHead","chain_getHead","chain_getHeader","chain_getRuntimeVersion","chain_subscribeAllHeads","chain_subscribeFinalisedHeads","chain_subscribeFinalizedHeads","chain_subscribeNewHead","chain_subscribeNewHeads","chain_subscribeRuntimeVersion","chain_unsubscribeAllHeads","chain_unsubscribeFinalisedHeads","chain_unsubscribeFinalizedHeads","chain_unsubscribeNewHead","chain_unsubscribeNewHeads","chain_unsubscribeRuntimeVersion","childstate_getKeys","childstate_getKeysPaged","childstate_getKeysPagedAt","childstate_getStorage","childstate_getStorageEntries","childstate_getStorageHash","childstate_getStorageSize","grandpa_proveFinality","grandpa_roundState","grandpa_subscribeJustifications","grandpa_unsubscribeJustifications","mmr_generateProof","mmr_root","mmr_verifyProof","mmr_verifyProofStateless","offchain_localStorageClear","offchain_localStorageGet","offchain_localStorageSet","payment_queryFeeDetails","payment_queryInfo","rpc_methods","state_call","state_callAt","state_getChildReadProof","state_getKeys","state_getKeysPaged","state_getKeysPagedAt","state_getMetadata","state_getPairs","state_getReadProof","state_getRuntimeVersion","state_getStorage","state_getStorageAt","state_getStorageHash","state_getStorageHashAt","state_getStorageSize","state_getStorageSizeAt","state_queryStorage","state_queryStorageAt","state_subscribeRuntimeVersion","state_subscribeStorage","state_traceBlock","state_trieMigrationStatus","state_unsubscribeRuntimeVersion","state_unsubscribeStorage","subscribe_newHead","sync_state_genSyncSpec","system_accountNextIndex","system_addLogFilter","system_addReservedPeer","system_chain","system_chainType","system_dryRun","system_dryRunAt","system_health","system_localListenAddresses","system_localPeerId","system_name","system_nodeRoles","system_peers","system_properties","system_removeReservedPeer","system_reservedPeers","system_resetLogFilter","system_syncState","system_unstable_networkState","system_version","transactionWatch_v1_submitAndWatch","transactionWatch_v1_unwatch","transaction_v1_broadcast","transaction_v1_stop","unsubscribe_newHead"]}}
2025-07-09 03:12:58          API-WS: received {"jsonrpc":"2.0","id":4,"result":{"ss58Format":0,"tokenDecimals":10,"tokenSymbol":"DOT"}}
2025-07-09 03:12:58          API-WS: received {"jsonrpc":"2.0","id":2,"result":{"specName":"polkadot","implName":"parity-polkadot","authoringVersion":0,"specVersion":1005001,"implVersion":0,"apis":[["0xc51ff1fa3f5d0cca",1],["0xdf6acb689907609b",5],["0x37e397fc7c91f5e4",2],["0x40fe3ad401f8959a",6],["0x17a6bc0d0062aeb3",1],["0x18ef58a3b67ba770",1],["0xd2bc9897eed08f15",3],["0xf78b278be53f454c",2],["0xaf2c0297a23e6d3d",12],["0x49eaaf1b548a0cb0",5],["0x91d5df18b0d2cf58",2],["0x2a5e924655399e60",1],["0xed99c5acb25eedf5",3],["0xcbca25e39f142387",2],["0x687ad44ad37f03c2",1],["0xab3c0572291feb8b",1],["0xbc9d89904f5b923f",1],["0x37c8bb1350a9a2a8",4],["0xf3ff14d5ab527059",3],["0x6ff52ee858e6c5bd",1],["0x91b1c8b16328eb92",2],["0x9ffb505aa738d69c",1],["0xfbc577b9d747efd6",1]],"transactionVersion":26,"systemVersion":1,"stateVersion":1}}
2025-07-09 03:12:58          API-WS: received {"jsonrpc":"2.0","id":1,"result":"0x91b171bb158e2d3848fa23a9f1c25182fb8e20313b2c1eb49219da7a70ce90c3"}
2025-07-09 03:12:58          API-WS: calling state_call {"id":6,"jsonrpc":"2.0","method":"state_call","params":["Metadata_metadata_versions","0x"]}
2025-07-09 03:29:20        RPC-CORE: call(method: Text, data: Bytes, at?: BlockHash): Bytes:: No response received from RPC endpoint in 60s
2025-07-09 03:29:20        API/INIT: error with state_call::Metadata_metadata_versions, rpc::state::get_metadata will be used
2025-07-09 03:29:20          API-WS: calling state_getMetadata {"id":7,"jsonrpc":"2.0","method":"state_getMetadata","params":[]}
2025-07-09 03:29:20          API-WS: disconnected from wss://rpc.polkadot.io: 1006:: Abnormal Closure
2025-07-09 03:29:20        RPC-CORE: getMetadata(at?: BlockHash): Metadata:: disconnected from wss://rpc.polkadot.io: 1006:: Abnormal Closure
2025-07-09 03:29:20        API/INIT: Error: FATAL: Unable to initialize the API: disconnected from wss://rpc.polkadot.io: 1006:: Abnormal Closure
    at #onProviderConnect (/Users/polkadot-api-debug/node_modules/@polkadot/api/cjs/base/Init.js:390:27)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)

③

2025-07-09 05:30:28          API-WS: socket error ErrorEvent {
  [Symbol(kTarget)]: WebSocket {
    _events: [Object: null prototype] {
      close: [Function],
      error: [Function],
      message: [Function],
      open: [Function]
    },
    _eventsCount: 4,
    _maxListeners: undefined,
    _binaryType: 'nodebuffer',
    _closeCode: 1006,
    _closeFrameReceived: false,
    _closeFrameSent: false,
    _closeMessage: <Buffer >,
    _closeTimer: null,
    _errorEmitted: true,
    _extensions: {},
    _paused: false,
    _protocol: '',
    _readyState: 2,
    _receiver: null,
    _sender: null,
    _socket: null,
    _bufferedAmount: 0,
    _isServer: false,
    _redirects: 0,
    _autoPong: true,
    _url: 'wss://rpc.polkadot.io/',
    _req: null,
    [Symbol(kCapture)]: false
  },
  [Symbol(kType)]: 'error',
  [Symbol(kError)]: Error: connect ETIMEDOUT 104.26.9.125:443
      at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1555:16) {
    errno: -60,
    code: 'ETIMEDOUT',
    syscall: 'connect',
    address: '104.26.9.125',
    port: 443
  },
  [Symbol(kMessage)]: 'connect ETIMEDOUT 104.26.9.125:443'
}
2025-07-09 05:30:28          API-WS: disconnected from wss://rpc.polkadot.io: 1006:: Abnormal Closure
2025-07-09 05:30:28          API-WS: calling system_health {"id":30,"jsonrpc":"2.0","method":"system_health","params":[]}
2025-07-09 05:30:28          API-WS: calling system_health {"id":18,"jsonrpc":"2.0","method":"system_health","params":[]}
2025-07-09 05:30:28          API-WS: disconnected from wss://rpc.polkadot.io: 1006:: Abnormal Closure
2025-07-09 05:30:28          API-WS: disconnected from wss://rpc.polkadot.io: 1006:: Abnormal Closure
2025-07-09 05:30:29          API-WS: connected to wss://rpc.polkadot.io
2025-07-09 05:30:29          API-WS: calling chain_getBlockHash {"id":1,"jsonrpc":"2.0","method":"chain_getBlockHash","params":[0]}
2025-07-09 05:30:29          API-WS: calling state_getRuntimeVersion {"id":2,"jsonrpc":"2.0","method":"state_getRuntimeVersion","params":[]}
2025-07-09 05:30:29          API-WS: calling system_chain {"id":3,"jsonrpc":"2.0","method":"system_chain","params":[]}
2025-07-09 05:30:29          API-WS: calling system_properties {"id":4,"jsonrpc":"2.0","method":"system_properties","params":[]}
2025-07-09 05:30:29          API-WS: calling rpc_methods {"id":5,"jsonrpc":"2.0","method":"rpc_methods","params":[]}

[rajk93]

@milc0x That's strange — the code snippet you shared works as expected on my end without any issues. Could you try using one of the alternative endpoints listed here and see if that resolves the problem?

[milc0x]

The error actually occurs intermittently on my end — most of the requests succeed, but sometimes they fail (about 1 failure per hour).

I am currently using the latest version(v16.4.1) of the API to debug the issue again.
I will also try using one of the alternative endpoints you suggested to see if that helps resolve the problem.

[milc0x]

@rajk93

I tried the latest v16.4.1 version, and this issue still exists.

2025-07-10 01:34:50          API-WS: connected to wss://rpc.polkadot.io
2025-07-10 01:34:50          API-WS: calling chain_getBlockHash {"id":1,"jsonrpc":"2.0","method":"chain_getBlockHash","params":[0]}
2025-07-10 01:34:50          API-WS: calling state_getRuntimeVersion {"id":2,"jsonrpc":"2.0","method":"state_getRuntimeVersion","params":[]}
2025-07-10 01:34:50          API-WS: calling system_chain {"id":3,"jsonrpc":"2.0","method":"system_chain","params":[]}
2025-07-10 01:34:50          API-WS: calling system_properties {"id":4,"jsonrpc":"2.0","method":"system_properties","params":[]}
2025-07-10 01:34:50          API-WS: calling rpc_methods {"id":5,"jsonrpc":"2.0","method":"rpc_methods","params":[]}
2025-07-10 01:34:50        RPC-CORE: getMetadata(at?: BlockHash): Metadata:: No response received from RPC endpoint in 60s
2025-07-10 01:34:50        API/INIT: Error: FATAL: Unable to initialize the API: No response received from RPC endpoint in 60s
    at #onProviderConnect (/Users/polkadot-api-debug/node_modules/@polkadot/api/cjs/base/Init.js:390:27)
2025-07-10 01:34:50          API-WS: received {"jsonrpc":"2.0","id":5,"result":{"methods":["account_nextIndex","archive_v1_body","archive_v1_call","archive_v1_finalizedHeight","archive_v1_genesisHash","archive_v1_hashByHeight","archive_v1_header","archive_v1_stopStorage","archive_v1_storage","archive_v1_storageDiff","archive_v1_storageDiff_stopStorageDiff","author_hasKey","author_hasSessionKeys","author_insertKey","author_pendingExtrinsics","author_removeExtrinsic","author_rotateKeys","author_submitAndWatchExtrinsic","author_submitExtrinsic","author_unwatchExtrinsic","babe_epochAuthorship","beefy_getFinalizedHead","beefy_subscribeJustifications","beefy_unsubscribeJustifications","chainHead_v1_body","chainHead_v1_call","chainHead_v1_continue","chainHead_v1_follow","chainHead_v1_header","chainHead_v1_stopOperation","chainHead_v1_storage","chainHead_v1_unfollow","chainHead_v1_unpin","chainSpec_v1_chainName","chainSpec_v1_genesisHash","chainSpec_v1_properties","chain_getBlock","chain_getBlockHash","chain_getFinalisedHead","chain_getFinalizedHead","chain_getHead","chain_getHeader","chain_getRuntimeVersion","chain_subscribeAllHeads","chain_subscribeFinalisedHeads","chain_subscribeFinalizedHeads","chain_subscribeNewHead","chain_subscribeNewHeads","chain_subscribeRuntimeVersion","chain_unsubscribeAllHeads","chain_unsubscribeFinalisedHeads","chain_unsubscribeFinalizedHeads","chain_unsubscribeNewHead","chain_unsubscribeNewHeads","chain_unsubscribeRuntimeVersion","childstate_getKeys","childstate_getKeysPaged","childstate_getKeysPagedAt","childstate_getStorage","childstate_getStorageEntries","childstate_getStorageHash","childstate_getStorageSize","grandpa_proveFinality","grandpa_roundState","grandpa_subscribeJustifications","grandpa_unsubscribeJustifications","mmr_generateProof","mmr_root","mmr_verifyProof","mmr_verifyProofStateless","offchain_localStorageClear","offchain_localStorageGet","offchain_localStorageSet","payment_queryFeeDetails","payment_queryInfo","rpc_methods","state_call","state_callAt","state_getChildReadProof","state_getKeys","state_getKeysPaged","state_getKeysPagedAt","state_getMetadata","state_getPairs","state_getReadProof","state_getRuntimeVersion","state_getStorage","state_getStorageAt","state_getStorageHash","state_getStorageHashAt","state_getStorageSize","state_getStorageSizeAt","state_queryStorage","state_queryStorageAt","state_subscribeRuntimeVersion","state_subscribeStorage","state_traceBlock","state_trieMigrationStatus","state_unsubscribeRuntimeVersion","state_unsubscribeStorage","subscribe_newHead","sync_state_genSyncSpec","system_accountNextIndex","system_addLogFilter","system_addReservedPeer","system_chain","system_chainType","system_dryRun","system_dryRunAt","system_health","system_localListenAddresses","system_localPeerId","system_name","system_nodeRoles","system_peers","system_properties","system_removeReservedPeer","system_reservedPeers","system_resetLogFilter","system_syncState","system_unstable_networkState","system_version","transactionWatch_v1_submitAndWatch","transactionWatch_v1_unwatch","transaction_v1_broadcast","transaction_v1_stop","unsubscribe_newHead"]}}
2025-07-10 01:34:50          API-WS: received {"jsonrpc":"2.0","id":3,"result":"Polkadot"}
2025-07-10 01:34:50          API-WS: received {"jsonrpc":"2.0","id":4,"result":{"ss58Format":0,"tokenDecimals":10,"tokenSymbol":"DOT"}}
2025-07-10 01:34:50          API-WS: received {"jsonrpc":"2.0","id":2,"result":{"specName":"polkadot","implName":"parity-polkadot","authoringVersion":0,"specVersion":1005001,"implVersion":0,"apis":[["0xc51ff1fa3f5d0cca",1],["0xdf6acb689907609b",5],["0x37e397fc7c91f5e4",2],["0x40fe3ad401f8959a",6],["0x17a6bc0d0062aeb3",1],["0x18ef58a3b67ba770",1],["0xd2bc9897eed08f15",3],["0xf78b278be53f454c",2],["0xaf2c0297a23e6d3d",12],["0x49eaaf1b548a0cb0",5],["0x91d5df18b0d2cf58",2],["0x2a5e924655399e60",1],["0xed99c5acb25eedf5",3],["0xcbca25e39f142387",2],["0x687ad44ad37f03c2",1],["0xab3c0572291feb8b",1],["0xbc9d89904f5b923f",1],["0x37c8bb1350a9a2a8",4],["0xf3ff14d5ab527059",3],["0x6ff52ee858e6c5bd",1],["0x91b1c8b16328eb92",2],["0x9ffb505aa738d69c",1],["0xfbc577b9d747efd6",1]],"transactionVersion":26,"systemVersion":1,"stateVersion":1}}
2025-07-10 01:34:50          API-WS: received {"jsonrpc":"2.0","id":1,"result":"0x91b171bb158e2d3848fa23a9f1c25182fb8e20313b2c1eb49219da7a70ce90c3"}
2025-07-10 01:34:50          API-WS: calling state_call {"id":6,"jsonrpc":"2.0","method":"state_call","params":["Metadata_metadata_versions","0x"]}

And another issue caused by similar error Error: No response received from RPC endpoint in 60s occurred in timeoutHandlers.

2025-07-10 01:46:52          API-WS: received {"jsonrpc":"2.0","id":9,"result":"Polkadot"}
[2025-07-09T16:46:52.939Z] Connected to chain: Polkadot
2025-07-10 01:46:52          API-WS: calling chain_getHeader {"id":10,"jsonrpc":"2.0","method":"chain_getHeader","params":[]}
2025-07-10 02:02:36        RPC-CORE: getHeader(hash?: BlockHash): Header:: No response received from RPC endpoint in 60s
[2025-07-09T17:02:36.855Z] Error: Error: No response received from RPC endpoint in 60s
    at #timeoutHandlers (/Users/polkadot-api-debug/node_modules/@polkadot/rpc-provider/cjs/ws/index.js:517:38)
    at Timeout._onTimeout (/Users/polkadot-api-debug/node_modules/@polkadot/rpc-provider/cjs/ws/index.js:185:70)
    at listOnTimeout (node:internal/timers:569:17)
    at process.processTimers (node:internal/timers:512:7)
2025-07-10 02:02:36          API-WS: calling system_health {"id":11,"jsonrpc":"2.0","method":"system_health","params":[]}
2025-07-10 02:02:36          API-WS: disconnected from wss://rpc.polkadot.io: 1006:: Abnormal Closure

[rajk93]

@milc0x

Since these are public endpoints, they can become overloaded with continuous requests, which might be causing the intermittent failures.

Yes, you can try using an alternate endpoint to see if it resolves the issue.

Another thing you can try is overriding the default timeout (60s) for the WsProvider. Here's how you can configure it:

const wsProvider = new WsProvider(
  'wss://rpc.polkadot.io',  // endpoint
  2500,                     // Default Auto-reconnect delay
  {},                       // Default Custom headers
  120000                    // Custom timeout in milliseconds (120s)
);

Please Let me know if this helps.