Can't boot after APFS conversion - SOLVED

[SweeneyD24]

Long story short, I downloaded the MacOS Catalina installer and got the error message that my SSD is not in APFS format.

Googled and found some instructions on how to convert to APFS in Recovery Mode without losing data.
The conversion was successful but now i get the error message when trying to boot on the SSD.

'Running bless to place boot files failed.'

(My MBP is booting directly to Recovery Mode since it cannot find a bootable volume)

Googled again and found this command to fix the error.

diskutil apfs updatePreboot /Volumes/Macintosh\ HD/
(Replace “/Macintosh\ HD/” with the name of the boot volume)

Tried it and found the below error message in the log.

“Unable to find boot helper partition"

Restarted the laptop. Same issue.

 

[SweeneyD24]

After a long and (tbh) depressing fight, I finally got it to work.

I eventually resorted to Install a new copy of macOS and after a long and painful wait for the OS to download and see if it's actually gonna work, i got the error message Could not create a preboot volume for APFS install.

I then proceed to run the command in Terminal (Recovery Mode) diskutil apfs updatePreboot /Volumes/Macintosh\ HD/ and to my great surprise, it executed without any error.

Say no more: Closed Disk Utility and selected my SSD as Startup Disk and Voilà!

Hope this might help.

EDIT: Forgot to mention - My SSD is now in APFS and even takes 30sec less to boot