Failed to load Java Extensions Pack

[Gary_Parden]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I re-installed cursor. After re-install
a) the gui left=hand pane had reverted to the vscode layout - the short horizontal bar for extensions, change control, etc. was gone. See screenshot.
b) I tried loading the java extensions pack . The only result was a short popup "Cannot read properties of undefined (reading ‘activeEditor)’.

Steps to Reproduce

1. uninstall cursor. Manually delete the user’s .cursor folder and the workspace Cursor folder
2. install cursor user download
3. start cursor
4. Open the java extensions pack link: Java | Cursor Docs

Expected Behavior

1. When I originally installed cursor. the GUI was white on a black background. After this re-install it is black on a white background.
2. in the left-hand pane, instead of a short horizontal tool bar for explore, change, extensions, etc, these have been incorporated into horizontal bars in the vertical pane. I think this is a vscode original behaviour, but don’t quote me on this, I’m not a vscode user.
3. I expected to see the 6 java extensions appear in they left-hand pane. They didn’t. Instead there was a brief popup message. See screenshot.

Screenshots / Screen Recordings

Operating System

Windows 10/11

Version Information

Version: 3.5.33 (user setup)
VSCode Version: 1.105.1
Commit: aac81804b986d739acab348ed96b8bea6e83cc50
Date: 2026-05-22T06:47:48.039Z
Layout: glass
Build Type: Stable
Release Track: Default
Electron: 39.8.1
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
OS: Windows_NT x64 10.0.26200

Additional Information

I originally did a full re-install because I was having issues with Java/Gradle:
The Gradle extension was unreliable. I could open the Gradle extension, from ‘Show View’, but it would generally not appear alongside extensions, and therefore could note be pinned.
We have a multi-project build, and sometimes inter-project references would not be recognised.
There was evidence that projects were either being built, or run as junit tests, with the wrong java versions,.
So I did a full re-install intending to investigate the java/Gradle errors.

There have been a couple of cursor upgrades in the last couple of weeks. I said yes to both, but I can’t remember on which dates exactly.

Does this stop you from using Cursor

Yes - Cursor is unusable

[Colin]

@Gary_Parden I think the experience you’re looking for is in the Editor Window (see the Editor Window → ) button in the upper right of your screenshot.

Read more about the Agents Window here! Both are available for users depending on workflow/preference.

[Gary_Parden]

Thanks @Colin , that was it.

However, it is only a work-around - it is still the case that if you follow the instructions to setup Cursor for Java ( Java | Cursor Docs ) , they fail with an unhelpful error message.

[Colin]

Can you share the unhelpful error message, and/or at which step you received it?

[Gary_Parden]

Sure.

I followed the instructions in link cursor.com|for|java

I had just re-installed Cursor and started it from the windows start menu. This opened an Agents window but not an Editor window.

I clicked on 'Extension Pack for Java, which is one large button.

The only response was a brief (2-3s) popup over the bottom right of the Agents window.

I suspect that this would have worked if I had opened an Editor window and ensured that it had window focus.

I also suspect, although I haven’t tried it, that opening a file or folder from the windows context menus only works if you have an already open and with-focus Editor window.

[Colin]

Thanks a lot. Seems like a bug on our side. I’ve filed it with the team.