ChatBedrockConverse: passing empty inferenceConfig object and empty system array causes Bedrock ValidationException when using Prompt Management #9310
Description
Checked other resources
- This is a bug, not a usage question. For questions, please use the LangChain Forum (https://forum.langchain.com/).
- I added a very descriptive title to this issue.
- I searched the LangChain.js documentation with the integrated search.
- I used the GitHub search to find a similar question and didn't find it.
- I am sure that this is a bug in LangChain.js rather than my code.
- The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package).
Example Code
According to AWS docs, if you use a prompt from Prompt management, you may not include inferenceConfig, system, additionalModelRequestFields, or toolConfig in the Converse request; doing so is treated as a forbidden “override.” AWS Documentation
import { ChatBedrockConverse } from "@langchain/aws";
const llm = new ChatBedrockConverse({
// Important: this is a Prompt Management ARN, not a base model id
model: "arn:aws:bedrock:ap-south-1:123456789012:prompt/abc123:1",
// I do not intentionally set temperature/maxTokens/system messages
// (they’re left undefined / absent)
});
await llm.invoke("Ping"); // or await llm.stream("Ping");Error Message and Stack Trace (if applicable)
D:\developer\repository\experimental\genai-adapter-v-90-final\node_modules\@aws-sdk\client-bedrock-runtime\dist-cjs\index.js:1829
const exception = new ValidationException({
^
ValidationException: Conflict encountered. Overriding 'inferenceConfig' during runtime is not yet supported
at de_ValidationExceptionRes (D:\developer\repository\experimental\genai-adapter-v-90-final\node_modules\@aws-sdk\client-bedrock-runtime\dist-cjs\index.js:1829:23)
at de_CommandError (D:\developer\repository\experimental\genai-adapter-v-90-final\node_modules\@aws-sdk\client-bedrock-runtime\dist-cjs\index.js:1649:25)
at processTicksAndRejections (node:internal/process/task_queues:105:5)
at async D:\developer\repository\experimental\genai-adapter-v-90-final\node_modules\@smithy\middleware-serde\dist-cjs\index.js:8:24
at async D:\developer\repository\experimental\genai-adapter-v-90-final\node_modules\@smithy\core\dist-cjs\index.js:121:20
at async D:\developer\repository\experimental\genai-adapter-v-90-final\node_modules\@smithy\middleware-retry\dist-cjs\index.js:254:46
at async D:\developer\repository\experimental\genai-adapter-v-90-final\node_modules\@aws-sdk\middleware-logger\dist-cjs\index.js:5:26
at async ChatBedrockConverse._streamResponseChunks (D:\developer\repository\experimental\genai-adapter-v-90-final\node_modules\@langchain\aws\src\chat_models.ts:923:26)
at async ChatBedrockConverse._generate (D:\developer\repository\experimental\genai-adapter-v-90-final\node_modules\@langchain\aws\src\chat_models.ts:839:24)
at async D:\developer\repository\experimental\genai-adapter-v-90-final\node_modules\@langchain\core\src\language_models\chat_models.ts:529:35 {
'$fault': 'client',
'$response': HttpResponse {
statusCode: 400,
reason: undefined,
headers: {
':status': 400,
date: 'Mon, 03 Nov 2025 11:59:23 GMT',
'content-type': 'application/json',
'content-length': '100',
'x-amzn-requestid': '7ce86070-cba5-4f82-8a99-f99aa06a922e',
'x-amzn-errortype': 'ValidationException:http://internal.amazon.com/coral/com.amazon.bedrock/'
},
body: ClientHttp2Stream {
_events: [Object],
_readableState: [ReadableState],
_writableState: [WritableState],
allowHalfOpen: true,
_maxListeners: undefined,
_eventsCount: 11,
[Symbol(shapeMode)]: true,
[Symbol(kCapture)]: false,
[Symbol(async_id_symbol)]: 31,
[Symbol(kSession)]: [ClientHttp2Session],
[Symbol(timeout)]: null,
[Symbol(state)]: [Object],
[Symbol(request)]: null,
[Symbol(proxySocket)]: null,
[Symbol(sent-headers)]: [Object: null prototype],
[Symbol(origin)]: 'https://bedrock-runtime.ap-south-1.amazonaws.com',
[Symbol(requestAsyncResource)]: [AsyncResource],
[Symbol(id)]: 1,
[Symbol(kHandle)]: [Http2Stream]
}
},
'$retryable': undefined,
'$metadata': {
httpStatusCode: 400,
requestId: '7ce86070-cba5-4f82-8a99-f99aa06a922e',
extendedRequestId: undefined,
cfId: undefined,
attempts: 1,
totalRetryDelay: 0
}
}Description
When ChatBedrockConverse is used with an Amazon Bedrock Prompt Management prompt (i.e., model is a Prompt ARN), two runtime fields are being sent even when they are effectively “empty”:
An inferenceConfig object whose properties (maxTokens, temperature, etc.) are undefined, but the object itself is present.
A system field that is an empty array when there are no system messages.
System Info
Node version: v22.17.1
@langchain/aws version: ^1.0.0
Platform: Windows 10 (win32 10.0.19045)