Linux KDE login redirect issue

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Linux KDE login redirect issue

Cursor launches correctly using the AppImage version.

However, when clicking “Log in” or “Sign up”, instead of opening the authentication page in Firefox, the system opens KDE Discover.

I manually opened the login page in Firefox and successfully logged into my Cursor account, but the application did not receive the authentication session and stayed logged out.

System:

  • Linux
  • KDE Plasma
  • Cursor AppImage 3.5.17-3.5.33
  • Firefox set as default browser

I also tested:
xdg-open https://cursor.com

This correctly opens Firefox.

The issue seems related to OAuth/deep-link callback handling on KDE/Linux.

Running with:
–no-sandbox
and
–disable-gpu

did not fix the login callback issue.

Would appreciate any workaround or guidance.

5

Hey, thanks for the detailed report. There are two separate issues here, so let’s go one by one.

  1. Login doesn’t get picked up in the IDE.
    On Linux, the login flow works differently than on macOS. There’s no cursor:// redirect back into the app. The browser stays on the confirmation page, and the IDE picks up the session in the background via polling. The most common reason this gets stuck is the default Electron setting Http: Proxy Support = override, which can silently block the polling requests.

Try this:

  • Open Settings Ctrl+,
  • Search for Http: Proxy Support
  • Change override to on
  • Restart Cursor and sign in again using the Log In button inside the app. Manually opening the login page won’t link the session to the IDE. You need the built-in flow with challenge/uuid.

If you’re using a proxy via env vars, that can also break it. Check:

env | grep -i proxy

Then run Cursor without them:

env -u http_proxy -u https_proxy -u HTTP_PROXY -u HTTPS_PROXY -u all_proxy cursor

Same fix helped in similar threads:

  1. KDE Discover opens instead of Firefox.
    If xdg-open https://cursor.com opens Firefox in a terminal, that still doesn’t mean the AppImage sees the same MIME defaults in its environment. Check the default handler for the scheme:
xdg-mime query default x-scheme-handler/https
xdg-mime query default x-scheme-handler/http

If it’s not Firefox, set it explicitly:

xdg-mime default firefox.desktop x-scheme-handler/https x-scheme-handler/http

Also check ~/.config/mimeapps.list. There shouldn’t be a mapping that points x-scheme-handler/https to Discover. This is a KDE and AppImage environment behavior, not a Cursor-specific one.

Let me know how it goes. If login still doesn’t get picked up, open Help > Toggle Developer Tools > Console during the login attempt and share the red errors, and we’ll dig deeper.