JetBrains ACP can not login

Where does the bug appear (feature/product)?

Somewhere else…

Describe the Bug

When I press the Cursor Login button in the JetBrains (WebStorm) AI Chat, it just comes back immediately with “Authentication failed: Invalid params.”

Steps to Reproduce

  • Install Cursor ACP in WebStorm
  • Open AI Chat
  • Set agent to Cursor
  • Send a message
    • Receive authentication required prompt
  • Push Cursor Login button

Expected Behavior

Operating System

Linux

Version Information

WebStorm 2026.1 EAP
Build #JBC-261.21849.27, built on February 25, 2026
Built from the branch: 261.21849
Source revision: 9a75b7067a259
Licensed to WebStorm EAP user:
Expiration date: March 27, 2026
Runtime version: 25.0.2+10-b329.66 amd64137.0.17-261-b62
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
Toolkit: sun.awt.X11.XToolkit
Linux 6.17.0-14-generic
Ubuntu 25.10; glibc: 2.42; desktop: GNOME (GNOME Shell 49.0)
Exception reporter ID: 15122531d2f089e-3921-4baf-81b1-f28fa8e602d8
Controller in Remote Development
GC: G1 Young Generation, G1 Concurrent GC, G1 Old Generation
Memory: 1912M
Cores: 8
Registry:
ide.experimental.ui=true
Non-Bundled Plugins:
com.intellij.plugins.macoskeymap (252.16512.17)
Key Promoter X (2024.2.2)
org.jetbrains.plugins.terminal (261.21849.37)
com.intellij.plugins.mnemonicKeymap (2026.1.1)
com.jetbrains.sh (261.21849.37)
com.intellij.ml.llm (261.21849.27)
String Manipulation (9.16.0)
Current Desktop: ubuntu:GNOME

Additional Information

ACP Logs

Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

Hi there!

It looks like you’re having trouble completing the authentication process when trying to use Cursor in JetBrains. We’re sorry for the inconvenience!

Authentication issues like this need to be handled by our support team directly. The forum team doesn’t have access to the authentication systems needed to troubleshoot these problems.

Please email [email protected] for assistance. Include as much detail as possible about:

  • What happens when you try to log in (the “Authentication failed: Invalid params” error you’re seeing)
  • Any error messages you see
  • The email address you’re using to sign in

The log details you’ve included in your post would also be helpful to share with the support team.

Our support team will be able to investigate and help resolve your issue. We’ve unlisted this thread to keep the forum organized. Thanks for understanding!

Hey, thanks for the report. I see in the system info it says “Controller in Remote Development”. That means WebStorm is running via Remote Development, so the cursor-agent is running on the remote host and can’t open a browser to log in. That’s why you get the instant “Invalid params” error.

ACP doesn’t support browserless login in these environments yet. I’ve passed this to the team. Ideally the agent should print a URL you can open manually when no browser is available, but that’s not in place yet.

As a possible workaround, try SSH’ing into the remote host and run agent login before starting WebStorm. There’s a chance the CLI will print a URL that you can open in your local browser. It might not work though. If it hangs, stop it with Ctrl+C.

If Remote Development isn’t required and you can use WebStorm locally, the login should work normally there.

Let me know how it goes.

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