[Bug]: Agent web search crashes after scraper/reranker failures with `Cannot read properties of undefined (reading 'role')`

[dabarbarian125]

What happened?

When using an Agent with LibreChat web search enabled, some searches complete successfully, but searches that hit blocked/protected pages (such as Reddit, Facebook and Pinterest) can fail and then crash the agent pipeline with:

Cannot read properties of undefined (reading 'role')

This appears to happen after upstream web-search component failures such as:

• Jina reranker 429 Too Many Requests
• Firecrawl scraper 403 Forbidden

Public-web queries can work, which suggests the core agent/tool flow is functional, but scraper/reranker failure handling may be leaving an invalid or undefined message in agent state.

Expected behavior

If a scraper or reranker fails for one or more sources, LibreChat should:

• handle the failed source gracefully
• continue with remaining usable results, or return a normal partial-failure message
• not crash in LangGraph / message reduction

Actual behavior

The agent thinks/searches for a bit, then fails with:

Something went wrong. Here's the specific error message we encountered: An error occurred while processing the request: Cannot read properties of undefined (reading 'role')

Backend logs show the crash occurs in the agent completion path and then inside LangGraph message coercion.

Version Information

LibreChat version: 0.8.3

Model:

• MiniMax 2.5 (via OpenAI-compatible/custom endpoint in LibreChat)

Web search setup:

• Search provider: SearXNG
• Scraper: Firecrawl
• Reranker: initially Jina, later changed to Cohere
• No explicit webSearch: block in librechat.yaml initially; using default web-search env/UI behavior

Control / A-B behavior

This query worked successfully and did not appear to return social/protected sources:

• Who was the first person to swim across the English Channel?

This suggests the issue is not a general model/tool failure and is more likely triggered by upstream search-source failures.

Additional notes

• Missing provider auth lookup errors also appeared in logs, for example:

  • No plugin auth SERPER_API_KEY found
  • No plugin auth SEARXNG_API_KEY found
  • No plugin auth FIRECRAWL_API_URL found
  • No plugin auth JINA_API_KEY found
  • No plugin auth COHERE_API_KEY found

However, since public-web queries can succeed, these do not appear to be the primary failure by themselves.

Hypothesis

It looks like failed scrape/rerank results may be leaving an undefined entry in the agent message state, which later crashes LangGraph when LibreChat tries to coerce messages and read .role.

What I already tried

• Switched reranker from Jina to Cohere
• Confirmed that a public-web query succeeds
• Observed that failures correlate with protected/social sources and upstream 403/429 errors

Version Information

ghcr.io/danny-avila/librechat:v0.8.3 028dd86ddb43 3.42GB 748MB U

Steps to Reproduce

1. Configure LibreChat 0.8.3 with Agent web search enabled
2. Use:
   • SearXNG for search
   • Firecrawl for scraping
   • Jina or Cohere for reranking
3. Use a query that tends to return protected/social pages (Facebook, Reddit, etc.)
4. Wait for the agent to search/scrape
5. Observe that upstream scrape/rerank errors occur
6. The request then aborts with Cannot read properties of undefined (reading 'role')

Failing prompt: "Find me the cheapest price on Lehman's stainless steel cider press"
Working prompt: "Who was the first person to swim across the English Channel?"

What browsers are you seeing the problem on?

Chrome

Relevant log output

#### Secondary crash

{"level":"error","message":"[api/server/controllers/agents/client.js #sendCompletion] Operation aborted Cannot read properties of undefined (reading 'role')","pregelTaskId":"962d881e-1370-5be3-b8b9-ac0ed57d29be","stack":"TypeError: Cannot read properties of undefined (reading 'role')\n    at _isMessageFieldWithRole (/app/node_modules/@langchain/core/dist/messages/base.cjs:396:21)\n    at coerceMessageLikeToMessage (/app/node_modules/@langchain/core/dist/messages/utils.cjs:136:52)\n    at Array.map (<anonymous>)\n    at BinaryOperatorAggregate.messagesStateReducer [as operator] (/app/node_modules/@langchain/langgraph/dist/graph/message.cjs:20:38)\n    at BinaryOperatorAggregate.update (/app/node_modules/@langchain/langgraph/dist/channels/binop.cjs:57:35)\n    at _applyWrites (/app/node_modules/@langchain/langgraph/dist/pregel/algo.cjs:177:35)\n    at _localRead (/app/node_modules/@langchain/langgraph/dist/pregel/algo.cjs:76:9)\n    at __pregel_read (/app/node_modules/@langchain/langgraph/dist/pregel/algo.cjs:560:96)\n    at ChannelRead.doRead (/app/node_modules/@langchain/langgraph/dist/pregel/read.cjs:57:20)\n    at /app/node_modules/@langchain/langgraph/dist/graph/state.cjs:664:49","timestamp":"2026-03-17T05:15:21.149Z"}


#### Upstream scraper failure


{"level":"error","message":"Error scraping https://www.facebook.com/groups/FarmDirectMinnesota/posts/1419044669191349/: Firecrawl API request failed: Request failed with status code 403","timestamp":"2026-03-17T05:15:19.488Z"}


#### Earlier upstream reranker failure with same downstream crash


AxiosError: Request failed with status code 429
    at async JinaReranker.rerank (/app/node_modules/@librechat/agents/dist/cjs/tools/search/rerankers.cjs:40:30)
    at async getHighlights (/app/node_modules/@librechat/agents/dist/cjs/tools/search/search.cjs:67:20)
    at async Object.processSources (/app/node_modules/@librechat/agents/dist/cjs/tools/search/search.cjs:502:13)


and then:


[api/server/controllers/agents/client.js #sendCompletion] Operation aborted Cannot read properties of undefined (reading 'role')

Screenshots

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