Time Machine won't back up to APFS drive

[Jethro!]

I have an external USB drive I have been using for my Time Machine backups. It was HFS formatted, until I recently FileVault encrypted it in High Sierra, not knowing that FV would also convert the drive/partition format to APFS. While I can view its files and restore from the USB drive, now Time Machine will not back up to it, apparently because of this file system incompatibility. I'm using this with an iMac, file system Journaled HFS+.

Anyone know how to fix this? Do I need to somehow convert the drive back to HFS+?

 

[techwarrior]

Time Machine is definitely not supported on APFS. Reformat it to HFS+, if there is anything of value on the drive, back it up first.

 

[Jethro!]

So I can't encrypt my external drive in High Sierra without it involuntarily converting it to APFS?

 

[Weaselboy]

So I can't encrypt my external drive in High Sierra without it involuntarily converting it to APFS?

I'm not quite sure how you ended up with APFS. But I used a HFS+ encrypted drive to backup High Sierra no problem. Just select this option.

 

[Jethro!]

View attachment 830196

I'm not quite sure how you ended up with APFS.

Me neither. But apparently when you use the Finder or FileVault to encrypt an external drive in High Sierra, it takes the liberties of converting it to APFS at the same time without informing you. It took about a week to do the encryption. I was wondering why it was taking so long -- now I know what it was up to.