FileVault stuck; can't stop or turn off. What to do?

Changing the setting for FileVault takes only a few seconds.

But once the setting is changed, the conversion of your drive begins. Slowly, in the background, each and every used block is read in (encrypted/decrypted on the fly if needed) and written back out again (encrypted/decrypted on the fly if needed).

That takes from all afternoon to a day or so, and proceeds only when your Mac is awake. You may not change the setting again until the conversion is complete. But your Mac can be used while the conversion is under way.

santabean2000 wrote:

2012 MBP 15" running 10.15.1

Can't update macOS software; discovered FileVault incomplete setup; can't turn off; can't finish. Stuck

If the conversion is in progress you have to let it complete first.

Can you post a screen shot of the dialog box—

When did this pop up, under what conditions?

see: Incomplete filevault encryption - endless restarts

https://discussions.apple.com/thread/8254112

You can erase the the "parent" drive and start over with an install and restore your user data

Boot into Internet Recovery (Command R) and from the dropdown menu: Utilities>  Disk Utility> View>Show All Devices

Recovery: https://support.apple.com/en-us/HT204904

How to erase a disk for Mac - https://support.apple.com/en-us/HT208496

How to reinstall macOS from macOS Recovery - https://support.apple.com/en-us/HT204904

Use FileVault to encrypt the startup disk on your Mac - Apple ...