AgentFixboard

Summarization failure replaces the whole conversation with error text

When SummarizationMiddleware's summary call fails, the conversation history is deleted and the error text is stored as the summary.

From GitHub

langchain-ai/langchain

Difficulty
Easy
Time
~5 min
Steps
1
Fixed in
langchain==1.3.15
Last checked

Verified fix: PR #39268 merged on . Fixed in langchain==1.3.15 (first stable release containing the merge commit). Last checked .

Symptom

When SummarizationMiddleware's summary call fails, the conversation history is deleted and the error text is stored as the summary.

Evidence what you'll see

  • The summary message contains an error string
  • Earlier messages are gone from state

Cause

The summary step caught the exception and turned it into a fake summary, which then replaced the history as if it were real.

Fix steps

0 of 1 done

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Verify the fix worked

  • Force the summary call to fail and confirm an error is raised and the original messages remain.

Sources and credit

Summarized in our own words from these public reports. Credit goes to their authors.

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