STDIO - Cannot connect without `OMIT_AUTH` since v0.14.1

[hesreallyhim]

Describe the bug
This is possibly a duplicate I think, but seems high priority and have some more context:

• Have only tried stdio
• Cannot connect to any server (locally installed, npx, locally built, etc.)
• Have tried entering MCP_PROXY_AUTH_TOKEN in Configuration, in Environment Variables, using prefilled link, etc.
• Upon hitting "Connect" - request sent to /health - response 200 OK HTML.
• Server says "Error Connecting to MCP Inspector Proxy - Check Console logs", which points to TypeError: Load failed, which directs to source code at checkProxyHealth.
• Tried running npx @modelcontextprotocol/inspector@0.14.0 - works fine
• npx @modelcontextprotocol/inspector@0.14.1 - fails like above.
• In Chrome: Couldn't connect to MCP Proxy Server SyntaxError: Unexpected token '<', "<!doctype "... is not valid JSON - seems like it's trying to parse response from /health like a JSON-RPC message.

[hesreallyhim]

it's something to do with the config I think... in 0.14.0:

Fetch finished loading: GET "http://localhost:6277/config"

in 0.14.1:

Fetch failed loading: GET "http://localhost:6277/config".

also 0.14.0 doesn't display this message:

Use this token to authenticate requests or set DANGEROUSLY_OMIT_AUTH=true to disable auth ... etc

So seems like big change between 0.14.0 and 0.14.1...

[olaservo]

Are you still having connection issues with the latest Inspector?

Here's what I see when starting Inspector and connecting to the latest Everything Server over stdio, there were some security-related changes related to a CVE that changed a few things in 0.14.1:

npx -y  @modelcontextprotocol/inspector@latest
Starting MCP inspector...
⚙️ Proxy server listening on localhost:6277
🔑 Session token: <token redacted>
   Use this token to authenticate requests or set DANGEROUSLY_OMIT_AUTH=true to disable auth

🚀 MCP Inspector is up and running at:
   http://localhost:6274/?MCP_PROXY_AUTH_TOKEN=<token redacted>

🌐 Opening browser...