claude-code - 💡(How to fix) Fix PostToolUse:Write hook error: 'Messages are required for agent hooks. This is a bug.' with CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1 [2 comments, 3 participants]

⎿ PostToolUse:Write hook error 3. Observe the banner: Read 1 file, recalled 1 memory, wrote 2 memories (ctrl+o to expand) — followed by two PostToolUse:Write hook error / Messages are required for agent hooks. This is a bug. lines. The error text "This is a bug." is presumably generated by the harness itself, which strongly suggests this is an internal invariant violation — the agent-hook runner is being invoked without the required messages field populated.

• The post-memory-write hook runs silently (no error), or Happy to provide more detail on request — e.g., exact error timing relative to tool output, or a full session transcript with memory file changes reproduced.

TL;DR

The most likely fix is to unset the CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS environment variable to avoid the experimental code path that triggers the post-write telemetry step failure.

Guidance

• The error message suggests an internal invariant violation due to the agent-hook runner being invoked without the required messages field populated.
• To verify the issue, run the reproduction steps and observe the banner for the PostToolUse:Write hook error messages.
• To mitigate the issue, unsetting the CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS environment variable can avoid the code path that triggers the error, although this may disable some experimental features.
• If the experimental features are necessary, ignoring the banner and error messages may be a temporary workaround, as the memory writes themselves succeed.

Notes

The issue appears to be specific to the experimental agent teams feature and the auto-memory pipeline. The provided workaround may not be suitable for all use cases, especially if the experimental features are required.

Recommendation

Apply workaround: Unset the CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS environment variable to avoid the experimental code path that triggers the post-write telemetry step failure. This is a safe and straightforward solution that can help mitigate the issue until a proper fix is available.