Vercel MCP OAuth fails: “App configuration error – redirect URL is invalid”

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1

Where does the bug appear (feature/product)?

BugBot

Describe the Bug

I can’t connect Vercel MCP in Cursor because OAuth keeps failing with “The app redirect URL is invalid”.
Authorize URL sample:

Steps to Reproduce

  1. Add Vercel MCP via “Add to Cursor”
  2. In Cursor, click “Needs login”
  3. Browser opens Vercel OAuth authorize page
  4. Error appears: “The app redirect URL is invalid”

Expected Behavior

OAuth should complete and return to Cursor via cursor:// callback, then Vercel MCP should connect.

Operating System

Windows 10/11

Version Information

  • OS: Windows 10 (10.0.19045)
  • Cursor version: 3.2.11
  • Browser: Chrome

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Additional Information

Could you check whether Cursor’s Vercel OAuth client redirect URI is correctly configured?

Does this stop you from using Cursor

No - Cursor works, but with this issue

5

Hey, thanks for the detailed report. This isn’t a Cursor-side bug. Cursor returns the cursor://anysphere.cursor-mcp/oauth/callback redirect correctly, and OAuth works fine for other MCP providers that have this URI registered.

The “The app redirect URL is invalid” error is coming from Vercel’s authorize endpoint before the callback ever returns to Cursor. This means Vercel hasn’t whitelisted cursor://anysphere.cursor-mcp/oauth/callback as a valid redirect URI in their OAuth client config for the MCP integration client_id=cl_KcWL599JrCOhI4n2lXPJJ8rkF4SqSbOf. Redirect URI registration is done on the provider side, so we can’t fix this unilaterally.

We saw the exact same issue recently with Linear MCP Linear MCP auth fails with “Invalid redirect URI” (cursor://anysphere.cursor-mcp/oauth/callback) and earlier with Slack. Both were fixed once the provider registered the URI.

I’ve reported this on our side. It also helps to ping Vercel support with the same request. The more signals they get, the faster they’ll pick it up. I can’t share an ETA since the fix depends on them. If there’s an update, I’ll post it in the thread.

8

Still broken Aug 11 2026 via Cursor Vercel plugin (649) in Grok Bot. Connect card shows but auth never completes — stays needsAuth, tools=0. Stripe/Notion/Gmail OAuth worked fine in the same session. Please whitelist Cursor’s OAuth redirect and fix the plugin auth path.

9

Hey, thanks for the update, @Ahmet. What you’re describing (needsAuth, tools=0, and Stripe/Notion/Gmail connecting fine in the same session) points to this being a Vercel OAuth issue, not something in your setup. The auth is getting stuck on Vercel before the flow can finish and return the token back to Cursor.

We’re tracking this issue. I can’t share an exact timeline since the final step depends on Vercel. It also helps if you ping their support with the same request. More reports usually means they pick it up faster.

Quick tracking ask: this thread originally was about the desktop error “The app redirect URL is invalid”, but your case is the Grok Bot plugin where auth hangs on needsAuth. The symptom is a bit different. Can you start a separate thread specifically for Grok Bot Vercel and mention plugin version 649, plus that Stripe/Notion/Gmail worked in the same session? That way we can track it cleanly on its own. I’ll share an update if I hear more.

10

@deanrie opened a dedicated Grok Bot thread as requested, with a Grok Bot iOS screenshot of Vercel’s “App configuration error - The app redirect URL is invalid” on plugin 649. Connector stays needsAuth / tools=0. Other official plugins in the same Grok Bot session connect fine.