Cursor Linux AppImage self-update downloads then rolls back: `Validation error: AppImage no longer comes with signature` (staff said fixed for all users 2026-10-17)

Context

Source(s): https://forum.cursor.com/t/cursors-linux-self-update-validation-error-appimage-no-longer-comes-with-signature/174891 Signal: 58 views; staff answer accepted, and staff posted two days later that it "should be fixed for all users now" (October 2026). Status: reported working by source, not reproduced by us (workaround only; root fix not confirmed).

Problem

On Linux, Cursor's in-app updater runs appimageupdatetool, zsync finishes and the checksum matches, but the updater then rejects the new file and restores the old one. Cursor stays on the old version (3.24.18) and offers the same update (3.25.6) again every time.

Error (redacted / normalized)

Validation error: AppImage no longer comes with signature
Restoring original file

Applies when

Cursor IDE AppImage on Linux, 3.24.18 updating to 3.25.6, October 2026.

Confirm it is this problem

1. Run the in-app update and watch its output. → expect: the two lines above after zsync completes.
2. Check Help > About after the restart. → expect: still the old version, with the same update offered again (our inference for where to check).

Not this when / boundary

The updater fails before validation (download or zsync errors), or Cursor was installed from a .deb/.rpm package rather than as an AppImage; the error above is specific to AppImageUpdate (our inference).

Root cause

Per Cursor staff: while a new version is still rolling out, the Linux updater can offer a build that isn't signed the same way as the AppImage downloaded from the website, so the updater refuses the swap and puts the old version back. The original poster noted that AppImageUpdate treats a signed-to-unsigned replacement as a failure.

Fix

1. Run the in-app update again. → expect: staff said on 2026-10-17 that the issue should be fixed for all users, so the update should now install (trying again is our inference from that announcement).
2. If it still rolls back, update by hand (the original poster's workaround; staff gave the same steps; workaround only): download the AppImage for your architecture (x64 or ARM64) from the official Cursor download page once it lists the new version.
3. Replace your current AppImage with it at the same file path and make it executable, e.g. chmod +x <path-to-Cursor.AppImage> (staff: keeping the same path keeps your launcher and desktop entry working). → expect: Cursor starts on the new version.

How to verify

After the update, Cursor reports the new version and stops offering the same update.

What did not work

Clicking update repeatedly just loops (the original poster).

Rollback

Keep a copy of the old AppImage until the new one starts normally, and put it back at the same path if needed (our inference).

Risks

Download only from the official Cursor download page or the links Cursor staff post; don't use AppImages from mirrors (our inference). Don't try to get around the check by turning off signature validation in AppImageUpdate; it exists to stop a swapped binary (our inference).

Verified scope

Cursor AppImage on Linux during the 3.25.6 rollout, October 2026.

Becomes obsolete when

Staff said on 2026-10-17 it should be fixed for all users; keep for users who hit it during a future rollout.