Replace failed geli partitioned disk in vers. 12.0

[G Brown]

I can't see in the documentation where or how this is handled. Many people have their main encrypted pool without a passphrase; however, all previous versions say you must have a passphrase to replace a failed disk:

Warning: Encrypted pools must have a valid passphrase to replace a faileddisk.Set a passphrase and back up the encryption key using the pool Encryption Operations (page 135) before attempting to replace the failed drive.

If one moves to 12.0 with a geli pool and no passphrase and then a disk fails, how does one replace the geli encrypted disk? Can one setup geli encryption for a failed disk with 12.0? Or is adding geli encryption not possible?

Under 11.3 would these people with no passphrase on their main pool have to move the system dataset off of the main encrypted pool in order to add a passphrase to the main pool and then continue with the documented replacement method?

Has anybody done this replacement under 12.0? TIA