Turn off Filevault on macOS

I'm trying to upgrade my Macbook Pro to macOS Monterey, however the installation can not be started due to the disk is encrypted by Filevault 😕 I have to turn off Filevault to disable disk encrpytion before installing macOS Monterey.

I found this support article on how turning off Filevault, but it does not work at all. There is nothing hint or error message after clicking the option Turn off Filevault.

After researching it for a while, I found this post via CLI command,

1sudo fdesetup disable

But above command also does not work, it exits with error code -69594.

1sudo fdesetup disable
2Enter the user name:kane
3Enter the password for user 'kane':
4FileVault was not disabled (-69594).

I found some articles said that the Filevault only can be disabled by the user whom enables it. I found below command to show the user whom enabled the Filevault, it's enabled by an unknown user! I don't have idea how enabling it.

1sudo fdesetup list -extended
2ESCROW  UUID                                                                     TYPE USER
3        2D3F7CA5-4ED4-4537-8DA2-98B1E3637954                             Unknown User

Finally I found below command line to disable Filevault though I don't know which user enabled it.

1diskutil apfs disableFileVault disk1s1 -user disk

Input the disk password when booting the macOS. The disabling Filevault will be processed in backgroud, you can retrieve the progress by below command,

1diskutil apfs list

Happy Monterey!