MacBook Pro M2 Pro: FileVault fails after macOS upgrade

Question

MacBook Pro M2 Pro: FileVault fails after macOS upgrade

Just upgraded a MacBook Pro M2 Pro from 26.3.1(a) to 26.4. Did a fresh install on the (just erased) internal disk, and reinstalled my configuration from a backup (migration assistant during the upgrade procedure). Turns out that, now, in 26.4, I cannot reactivate Filevault on the internal system disk. The procedure asks me for my password, starts to mark Filevault as activated and then, after a few seconds and a message that I can't read as it only remains on the screen for less than half a second, returns to Filevault inactivated state.

I've tried to use SOS in Disk Utility to repair the system disk. It did not find any error and the problem is still there.

This may force me to return to 26.3.1(a) if no solution is found. I may also try to upgrade the (encrypted) system disk from 26.3.1(a) instead of doing a fresh install (quite a waste of time).

Is this issue already known?

Posted on Mar 26, 2026 4:19 AM

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Answer 1

Top-ranking reply

tbirdvet

Level 6

17,777 points

Mar 26, 2026 4:31 AM in response to DenisMaillard

I and others had a similar issue. You cannot use the UI menu to turn on. Open terminal and enter this command

sudo fdesetup enable then enter your PW and user name, etc. This will activate FileVault. This has been reported to Apple as a bug (does not impact all users for some reason). I started to have this issue with 26.3.1

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Answer 2

tbirdvet

Level 6

17,777 points

Mar 26, 2026 3:33 PM in response to DenisMaillard

I have tried upgrading from Sequoia which all worked fine then not with Tahoe 26.3. I also erased and reinstalled the OS and no change. Now can only use terminal for activation. No issue turning off from the UI menu, just turning on is the issue. I have another Mac and I do not have this issue. Go figure.

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Answer 3

Mar 26, 2026 5:04 AM in response to tbirdvet

Thank you. In the meantime, I had downgraded to 26.3.1 (a). Your command allowed me to reactivate Filevault on this version. I hadn't yet tried to reactivate it through System Settings, so I don't know if it worked there. When I upgraded from 26.3 to 26.3.1, i just upgraded rather than doing a fresh install. So I don't know whether activating Filevault from System Settings worked in 26.3.1 on my macBook. This means I'll have to redo the upgrade and use your Terminal workaround to activate Filevault on 26.4. As I said, quite a waste of time, but, at least, your reply will allow me to upgrade. Thanks again.

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