Pain point · Integrations · Blocks work
MCP initialization notification is rejected, preventing sessions
1 source thread · first seen 2026-09
Summary
Outline returns HTTP 400 for the MCP `notifications/initialized` message after successful OAuth and initialization. Claude Code then stops the session and cannot list Outline tools.
- Affects
- Claude Code users connecting to Outline's MCP server
Evidence
Excerpts are copied word for word from the source; follow the link to read it in full.
“Outline sends a 400 response”