Cannot install pyrefly extension

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Installation of pyrefly fails with the follow errors in the logs:

2026-03-05 11:14:19.044 [error] [Window] Failed: Server returned 503
    at ZFu.queryRawGalleryExtensions (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:46614:43512)
    at async ZFu.queryGalleryExtensionsWithAllVersionsAsFallback (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:46614:36203)
    at async ZFu.getExtensionsUsingQueryApi (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:46614:29716)
    at async ZFu.getExtensions (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:46614:28394)
    at async _nd.getDependenciesAndPackedExtensionsRecursively (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:49740:1082)
    at async _nd.getOtherUntrustedPublishers (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:49740:790)
    at async _nd.checkForTrustedPublishers (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:49736:18248)
    at async _nd.installFromGallery (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:49736:9263)
    at async vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:47790:51480
2026-03-05 11:14:19.045 [error] [Window] Server returned 503: Failed: Server returned 503
    at ZFu.queryRawGalleryExtensions (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:46614:43512)
    at async ZFu.queryGalleryExtensionsWithAllVersionsAsFallback (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:46614:36203)
    at async ZFu.getExtensionsUsingQueryApi (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:46614:29716)
    at async ZFu.getExtensions (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:46614:28394)
    at async _nd.getDependenciesAndPackedExtensionsRecursively (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:49740:1082)
    at async _nd.getOtherUntrustedPublishers (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:49740:790)
    at async _nd.checkForTrustedPublishers (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:49736:18248)
    at async _nd.installFromGallery (vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:49736:9263)
    at async vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:47790:51480 Server returned 503
2026-03-05 11:14:23.458 [error] [Network] #23: https://marketplace.cursorapi.com/open-vsx-mirror/vscode/asset/meta/pyrefly/0.55.0/Microsoft.VisualStudio.Code.Manifest?targetPlatform=win32-x64 - error GET Failed to fetch

Steps to Reproduce

  1. Open extensions view
  2. Search for pyrefly
  3. Click “Install”

Expected Behavior

Pyrefly installs successfully.

Screenshots / Screen Recordings

image (4).png
image (4).png509×146 6.74 KB

Operating System

Windows 10/11

Version Information

Version: 2.6.12 (system setup)
VSCode Version: 1.105.1
Commit: 1917e900a0c4b0111dc7975777cfff60853059d0
Date: 2026-03-04T21:41:18.914Z
Build Type: Stable
Release Track: Default
Electron: 39.6.0
Chromium: 142.0.7444.265
Node.js: 22.22.0
V8: 14.2.231.22-electron.0
OS: Windows_NT x64 10.0.22631

Additional Information

This makes cursor unusable for me, because I am trying to use Pyrefly as an alternative language server to Cursor Pyright which I am also unable to get to work properly: Cursor Pyright exceedingly slow

Does this stop you from using Cursor

Yes - Cursor is unusable

3

Hey, this is a 503 from our extensions marketplace mirror. This can happen when an extension is brand new on Open VSX or hasn’t fully synced yet.

A temporary workaround you can try right now:

  • Go to Open VSX Registry and download the .vsix file for your platform
  • In Cursor, open the Command Palette Ctrl+Shift+P and run Extensions: Install from VSIX...
  • Pick the file you downloaded

I also noticed you mentioned Pyright being slow in another thread. I replied there with a few settings that might help for now.

Let me know if the manual install works.

1 Like
4

Hi @Max_Gardner , I’m from the Pyrefly team and would love feedback about the tool if you are able to get it working with cursor.

1 Like
5

Manual install of pyrefly worked, and it is fast!

6

Should I disable Cursor Pyright completely now or just leave it with "cursorpyright.disableLanguageServices": true???

7

Sorry for the delay - I’ll wait for an authoritative answer from Cursor folks, but looking at other posts: Cursor Pyright automatically installed even I uninstall it you probably just want to update the settings.json mentioned in that post to disable, but not uninstall the Cursor Pyright extension as it will auto install itself again.

Given you have been using Pyrefly for a few weeks now, do you have any feedback? Have you been using type checking diagnostics or just the code navigation functionality?

8

Interestingly enough, today it seems like go-to-ref stopped working with Pyrefly. Go-to-def still works, but not the reverse. Any ideas?

9

Can you confirm which version of Pyrefly you are using?

11

0.55.0

12

Can you try upgrading to the latest version (currently 0.58) and let me know if you still see the issue? Try putting a pyrefly.toml file in the root of your project workspace. If we can’t detect the project workspace root, then we can have trouble building the index that powers find references.

14

I updated to 0.58 and created the pyrefly.toml as you suggested. Find references is still not working. This was working fine about a week ago so I’m not sure what happened.

15

I tried restarting the Pyrefly client a few times and noticed I was getting some errors, perhaps its related??

…
INFO Validated open files and committed transaction.
INFO Language server processed event `RecheckFinished` in 0.00s (0.00s waiting)
INFO Language server processed event `LspResponse` in 0.00s (0.00s waiting)
INFO Handling non-canceled request pyrefly/textDocument/typeErrorDisplayStatus (1)
INFO Language server processed event `LspRequest(pyrefly/textDocument/typeErrorDisplayStatus)` in 0.00s (0.00s waiting)
INFO Handling non-canceled request textDocument/documentSymbol (2)
INFO Language server processed event `LspRequest(textDocument/documentSymbol)` in 0.00s (0.00s waiting)
INFO Handling non-canceled request textDocument/inlayHint (3)
INFO Language server processed event `LspRequest(textDocument/inlayHint)` in 0.01s (0.00s waiting)
INFO Handling non-canceled request textDocument/foldingRange (4)
INFO Language server processed event `LspRequest(textDocument/foldingRange)` in 0.00s (0.00s waiting)
INFO Handling non-canceled request textDocument/semanticTokens/full (5)
INFO Language server processed event `LspRequest(textDocument/semanticTokens/full)` in 0.00s (0.00s waiting)
INFO Handling non-canceled request textDocument/documentSymbol (6)
INFO Language server processed event `LspRequest(textDocument/documentSymbol)` in 0.00s (0.00s waiting)
[Error - 7:49:35 PM] Notify file events failed.
Message: Client is not running
Code: -32096

16

Thanks for trying that and sorry it’s still not working. I created a ticket to track it here: Pyrefly can't find references in Cursor · Issue #3000 · facebook/pyrefly · GitHub

17

Thanks for the report! Sorry about your issues. If you see this happen again, would you be able to grab the output of the Pyrefly language server window instead of the Pyrefly trace? it looks like a crash and the trace only shows traffic and not crash logs.

19

Just upgraded to 0.59.1 and the issue seems to have resolved. If I notice it again I’ll be sure to update here.