Cursor not starting up - error occurred in the main process

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1

When trying to startup Cursor on Windows 11, I keep getting this error message. I’ve restarted.
I’ll attempt a reinstall. This is the second time in a month I’ve fought this issue. This is on my work account / enterprise version. The app worked fine on Friday, June 12th.

I’ve rebooted, as well as ran as admin. Cursor.exe version 3.1.17.
From the error below, the file path dead ends at C:\Program Files\cursor\resources\app. There is no \app\out. Could be my company anti-virus?

The error dialog I do get reads like this:

A JavaScript error occurred in the main process

Uncaught Exception:
Error [ERR_MODULE_NOT_FOUND]: Cannot find module ‘C:\Program Files\cursor\resources\app\out\main.js’ imported from C:\WINDOWS\system32
at finalizeResolution (node:internal/modules/esm/resolve:279:11)
at moduleResolve (node:internal/modules/esm/resolve:873:10)
at defaultResolve (node:internal/modules/esm/resolve:997:11)
at #cachedDefaultResolve (node:internal/modules/esm/loader:731:20)
at ModuleLoader.resolve (node:internal/modules/esm/loader:708:38)
at ModuleLoader.getModuleJobForImport (node:internal/modules/esm/loader:310:38)
at onImport.tracePromise.proto (node:internal/modules/esm/loader:664:36)
at TracingChannel.tracePromise (node:diagnostics_channel:350:14)
at ModuleLoader.import (node:internal/modules/esm/loader:663:21)
at node:electron/js2c/browser_init:2:141465

5

Reinstall worked.

7

What you ran into is a known Windows auto-update issue. When Cursor updates (it kicks off when you close the app), it removes the old files first and then writes the new ones. If something interrupts that second step, you’re left with a partial install missing out\main.js — which is exactly the ERR_MODULE_NOT_FOUND crash you saw. Corporate antivirus/EDR holding onto files during the swap is one of the most common triggers, so your hunch about the company AV is a good one.

Since it’s bitten you twice, two things will stop it recurring:

  1. Add Cursor’s install folder to your AV/Defender exclusions. Ask your IT team to exclude C:\Program Files\cursor so the antivirus doesn’t lock files mid-update. This is the most important step on a managed/enterprise machine.
  2. Switch updates to manual so an interrupted auto-update can’t break the install. Open Settings (Ctrl+,), search update mode, and set Update: Mode to manual (or none). If you’d rather edit settings.json directly, it’s "update.mode": "manual". You can then update on your own schedule by grabbing the latest build from cursor.com when you’re ready.

This is a known issue our team is tracking, so it’s nothing you did wrong on your end. If it comes back after the AV exclusion, reply here and I’ll dig in further.