Cause: macOS Gatekeeper blocking the app because the DMG was downloaded from an unidentified developer (even if it’s genuine Apple software, repackaged DMGs can trigger this).

Solution:
Right-click (or Control-click) iMovie.app and select Open. Then click Open in the dialog that appears. This adds the app to your approved list.

For security, run this Terminal command after downloading any iMovie_10.2.5.dmg:

codesign -dv --verbose=4 /Volumes/iMovie\ 10.2.5/iMovie.app

A genuine Apple-signed iMovie will show:

If you see adhoc or any third-party identifier, delete the DMG immediately.

Apple maintains a catalog of signed .pkg and .dmg files for system updates. A technically inclined user can:

Warning: This requires parsing complex XML. Only attempt if you are comfortable with macOS internals.

In the world of digital content creation, iMovie remains a cornerstone application for Apple users. It is free, powerful, and regularly updated. Yet, many users seeking older or unofficial versions stumble upon cryptic filenames like "iMovie 1025 dmg upd." While the name may sound like a legitimate update, it is almost certainly a dangerous trap. Understanding why can protect your data and your device.

Short answer: No.

Apple has never released an iMovie version 10.25, let alone “1025.” The current and previous iMovie versions follow a logical numbering system:

A filename like iMovie_1025.dmg or iMovie 1025 upd.dmg is not from Apple. It’s likely one of the following:

If you cannot find the update in the App Store, it is usually due to one of two reasons:

Assuming you have obtained a genuine iMovie_10.2.5.dmg file (verified by checking its SHA-256 hash or code signature), follow these steps:

Yes, if:

No, if: