Decrypting HD taking forever

sy195 wrote:

I by mistake during initial setup select encryption option which encrypted the HD very quick, but when try to update OS to Catalina, it advised to choose other drive as this drive is being encrypted. I found on apple forum that, once encryption is completed, turn off the FileVault, I tried but the progress bar does not move. I started the Mac, initially it showed 15 mins left, but after some time, same message again "more than day to decrypt"

Please advise how to resolve this? as I need to upgrade to Catalina.

Thanks

This can take days—

Decryption occurs in the background as you use your Mac, and only while your Mac is awake and plugged in to AC power. You can check progress in the FileVault section of Security & Privacy preferences.

https://support.apple.com/en-us/HT204837

Changing the setting for Encrypted/not-Encrypted takes less than a minute.

Changing your entire drive over requires that every used block be read in one way and written out the other way. In the meantime, you can do Many (but not all) ordinary operations and MacOS will work-around that your drive is undergoing re-construction.

That reconstruction in either direction takes a day, sometimes more. It runs at low priority in the background (so that you can do ordinary tasks but NOT re-install) and stops running if your Mac goes to sleep.

You can't try to change the setting again until it completes.