Why is Convert to APFS Failing?
Solution 1:
The only macOS version that can boot from a APFS container is High Sierra. In your case, the Apple_HFS volume does not contain not High Sierra. There is no way to convert to APFS and remain bootable.
Why is Convert to APFS Failing?
Solution 1:
The only macOS version that can boot from a APFS container is High Sierra. In your case, the Apple_HFS volume does not contain not High Sierra. There is no way to convert to APFS and remain bootable.