[Solved] Mac freezes after login. Can't Turn Off FileVault

Problem Context

First i realised that my Mac freezes every morning i tried to log in after sleep mode. I figured out that the problem is an older Mac hardware with a newer SSD which is encrypted via FileVault. Sadly it was not possible to turn of the FileVault disk encryption via GUI. The button is disabled or does not do anything when I select "Turn Off FileVault..."

Solution

I spent hours and it was tricky to find a working solution. In the end this worked for me:

Step 1: Open Terminal (Spot search Terminal)

Step 2: Find out encrypted disk ID (e.g. disk1s5) by typing in:

diskutil list

Step 3: Replace <disk ID> and <password> accordingly

diskutil apfs disableFileVault <disk ID> -user disk -passphrase <password> 

Step 4 (optional): Track progress by opening:

System Preferances > Security & Privacy > FileVault

Be alert that Step 3 might take few hours to decrypt. Provide sufficient battery or connect to AC

I hope this could solve your issue.