I'm using the OAuth Debugger, but after I complete consent, the MCP Jam fails to proceed

[rgs258]

It just hangs her in my browser (this is safari. I've also tried Chrome and Firefox):

MCP Jam hangs here: (corrected the following image)

[dosubot]

Hi @rgs258! I'm Dosu and I’m helping the inspector team.

This looks like a known issue. Issue #1535 reports the same behavior—OAuth consent completes successfully and shows "OAuth authorization code was sent successfully," but the flow hangs during the token exchange step.

The root cause appears to be an encoding issue with the PKCE code_verifier parameter when it's sent as application/x-www-form-urlencoded during token exchange. The same OAuth server works correctly with other tools like Postman, suggesting this is specific to MCP Inspector's implementation.

This issue is currently unresolved. You may want to add your details to #1535 to help track the scope of the problem, particularly:

• Which OAuth provider you're using
• Any error messages in your browser's developer console (Network tab → look for failed requests to the token endpoint)

To reply, just mention @dosu.

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[ignaciojimenezr]

this pr should solve it:
#1543
merging soon!

[rgs258]

I'm not sure if that's my issue. Here's the network tab open when I try to replay that auth url:

[rgs258]

Note: I'd messed up with my screen shot in the ticket. I just corrected it to show MCP Jam on the screen where the auth flow has hung. Once the auth flow hangs, the only option in the flow is to click reset. As such, I'm never able to proceed in the flow.

[rgs258]

Note, this is only in the Mac OS app - npx seems to work fine.

Also, THANK YOU all for such a great app! It is VERY helpful and we've found nothing else that this feature rich for our purpose of developing our mcp tools and auth flows.