MCP authentication broken in v2.75.x

[Lynxhide777]

Bug Report

Description

MCP (Model Context Protocol) authentication fails in versions 2.75.0 through 2.75.3, but works correctly in
v2.72.7. The OAuth endpoint appears to be missing or changed.

Environment

• OS: macOS (Apple Silicon), Windows
• Supabase CLI version (broken): 2.75.0, 2.75.1, 2.75.2, 2.75.3
• Supabase CLI version (working): 2.72.7
• MCP client: Claude Code

Steps to Reproduce

1. Install Supabase CLI v2.75.x
2. Configure MCP server in Claude Code to use local Supabase CLI with the .mcp.json configuration shown on supabase studio: "{
   "mcpServers": {
   "supabase": {
   "type": "http",
   "url": "http://127.0.0.1:54321/mcp"
   }
   }
   }"
3. Run claude /mcp and try to authenticate

Expected Behavior

MCP tools should authenticate successfully.

Actual Behavior

Authentication fails with the following error:

Error: HTTP 404: Invalid OAuth error response: ZodError: [
  {
    "expected": "string",
    "code": "invalid_type",
    "path": [
      "error"
    ],
    "message": "Invalid input: expected string, received undefined"
  }
]. Raw body: {"message":"no Route matched with those values"}

Analysis

The error "no Route matched with those values" suggests an OAuth endpoint that existed in v2.72.7 has been removed or its path changed in v2.75.x.

Workaround

Downgrade to v2.72.7