NightlyCursor+Slack MCP plugin still does not work

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

It is already
Version: 3.7.39
but you still have not fixed this problem. Slack integration does not work with cursor-nightly - #20 by Eugen_Konkov

Steps to Reproduce

  1. Try to connect Slack MCP Plugin with CursorNightly

Operating System

MacOS

Version Information

Version: 3.7.39
VS Code Extension API: 1.105.1
Commit: 142089e1157f04e847f3960d82a9a8d61d25f7c9
Date: 2026-06-14T01:39:43.144Z
Layout: editor
Build Type: Nightly
Release Track: Nightly
Electron: 39.8.1
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
xterm.js: 6.1.0-beta.256
OS: Darwin arm64 25.3.0

Does this stop you from using Cursor

No - Cursor works, but with this issue

5

I want to note, that Atlassian MCP connection works well. It redirects to the correct page and authenticate.

7

You’re right that it isn’t fixed yet for the standalone Cursor Nightly app, and your Atlassian observation is a useful clue. Different MCP providers register their OAuth callbacks differently. Atlassian’s setup accepts the standalone Nightly app’s callback, but Slack’s OAuth configuration currently only accepts the regular Cursor app’s callback scheme, so Slack MCP auth fails specifically on the standalone Nightly download. This is a known limitation on our side, and we’re working on a change to the connection flow that will fix it for the standalone app.

In the meantime, the reliable workaround is to run the regular Cursor app on the Nightly channel instead of the separate Nightly download:

  1. Install the standard Cursor app from Cursor · Download
  2. Open Cursor Settings → Beta → Update Access and select Nightly

You’ll still get nightly builds, but since it’s the regular app it uses the callback scheme Slack accepts, so Slack MCP connects normally.

One note since it came up before: your standalone Nightly app keeps its own separate settings, so doing this won’t delete or overwrite any of your existing Nightly configuration.

I’ll update this thread once the fix for the standalone app ships.