Claude Desktop on macOS breaks filesystem MCP servers after an auto-update
inddev · ghdev · 2026-07-22
Claude Desktop macOS regression breaks filesystem MCP servers
The reporter says that after Claude Desktop auto-updated, all tool calls to @modelcontextprotocol/server-filesystem configured through classic mcpServers started failing on macOS.
What they tested
- Two Macs, two Claude Desktop versions, both on macOS 26.5.2.
- Two package generations of server-filesystem:
- 2026.x rewrite shape: server initializes and lists tools, but every tool call fails instantly with Tool execution failed; logs show no tools/call ever arrives.
- 2025.8.21 pre-rewrite shape: tools/list works over raw stdio, but Claude Desktop says This connector has no tools available, so tools are silently dropped at registration.
- A minimal custom stdio server using the current SDK and registerTool without outputSchema works fine, suggesting the regression is specific to this connector/server shape.
Context
The issue is linked to similar Windows/macOS reports and appears to be a Desktop-side regression rather than a problem with the filesystem server itself.
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