Claude Desktop: tool_result POST fails with side_channel_waiting_key_absent (Filesystem connector appears broken) #4543
Description
yeungman
Issue body actions
- Error: side_channel_waiting_key_absent on endpoint tool_result
- Request ID from your log: req_011CdG5CtZqaXRHAgjaShMu1
- Timestamp: 2026-07-21 16:30:35 UTC
- What happened: Filesystem tool call completed locally, POST of result back to claude.ai returned 404 with that error code, causing the connector to appear broken
- App version: 1.24012.1, macOS Tahoe 26.5.1
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