fix: Skip empty AI messages in output_langchain to prevent API rejection#980
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frdel merged 1 commit intoagent0ai:developmentfrom Feb 1, 2026
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Empty or whitespace-only AI messages cause API validation errors with strict providers (OpenAI, Z.ai, GLM): "Assistant messages must have either content or tool_calls" This is a companion fix to PR agent0ai#927 (response.py KeyError fix). When that fix returns an empty string instead of crashing, the empty string can become an empty AIMessage that fails API validation. Changes: - Pre-compute content before creating message objects - Skip AI messages where content is None, empty, or whitespace-only - Human messages are not filtered (they can be empty per spec) Tested on 4 production A0 instances.
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To add to the above, I found this to be true when using Venice, A0-Venice, Opus, Grok 4.1 Fast. So, definitely not just GLM. |
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Thank you! |
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Feb 24, 2026
…ages fix: Skip empty AI messages in output_langchain to prevent API rejection
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Problem
Empty or whitespace-only AI messages cause API validation errors with strict providers (OpenAI, Z.ai, GLM):
Root Cause
This is a companion fix to PR #927 (response.py KeyError fix). When that fix returns an empty string instead of crashing, the empty string can become an empty
AIMessagethat fails API validation.The
output_langchain()function createsAIMessageobjects without validating that content exists.Solution
Testing
Deployed and validated on 4 production A0 instances running Z.ai/GLM providers.
Changes
python/helpers/history.py: Modifiedoutput_langchain()function (lines 519-533)