Linux KDE login redirect issue

Support Help
, ,
1

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.

6

This no longer appears to work, since it no longer seems to be possible to open the cursor settings from the login screen. Ctrl+` and trying to enter the setting through right clicking the cursor icon both do nothing.

7

To open Settings, you first need to enter editor mode. Open a folder or an empty editor window, then the full UI will load and the hotkeys will start working. After that, you can open Settings with Ctrl+Shift+,.

Try that and let me know if you can sign in after changing Http: Proxy Support to on.

8

What I mean is, I can’t get to editor mode.

I can’t get past this screen.

image
image1277×797 21.6 KB

9

Thanks, that makes sense now. On that welcome screen, the full UI isn’t loaded yet, so Settings and hotkeys don’t work. You really can’t get to editor mode from there. So we’ll change the setting directly in a file and skip the UI.

  1. Fully quit Cursor.

  2. Open or create the settings file:

mkdir -p ~/.config/Cursor/User
nano ~/.config/Cursor/User/settings.json
  1. Add this. If the file isn’t empty, just put this line inside the existing { }:
{
  "http.proxySupport": "on"
}

Save it.

  1. Start Cursor without proxy env vars, then try the Log In button inside the app:
env -u http_proxy -u https_proxy -u HTTP_PROXY -u HTTPS_PROXY -u all_proxy cursor

Important: log in using the Log In button in the app, not by opening the login page in your browser manually. Only the built-in flow will link the session to the IDE.

If your browser still opens KDE Discover instead of Firefox, check and set the default handler for the scheme:

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

If login still won’t get picked up, open Help > Toggle Developer Tools > Console while trying to sign in, then share any red errors. Also tell me your Cursor version and your distro and DE. Let me know how it goes.