MCP Server Connection Failure - 2025-10-29

Incident Summary

Date: October 29, 2025
Severity: Medium
Status: ✅ RESOLVED
Component: MCP_DOCKER (Obsidian MCP Server)
Resolution Time: < 30 minutes

Symptoms

• Unable to connect to Obsidian MCP server
• Connection refused errors on host.docker.internal:27124
• Error code: [Errno 111] Connection refused
• All MCP_DOCKER tool calls failing with HTTPSConnectionPool errors

Root Cause ✓ CONFIRMED

Root Cause: Obsidian application was not running on the host system.

The MCP server for Obsidian requires the Obsidian desktop application to be actively running. When the application is closed, the MCP server stops accepting connections, resulting in “Connection refused” errors.