I have two FreeNAS servers running version 9.10 on a HP MicroServer Gen 8. The main server has 16 GB RAM with a Intel(R) Xeon(R) CPU E3-1220L V2 @ 2.30GHz while the secondary has 8 GB RAM and a Intel(R) Celeron(R) CPU G1610T @ 2.30GHz. These two replicate data in both directions for off site backup. I recently upgraded them both to FreeNAS 11 U2 while also taking the opportunity to migrate backups from ISCSI ZVOL to Datasets. This meant replicating the new datasets.
However I kept facing errors while importing the ZPOOL on both of these servers; the error always seemed to relate to the replicated data. I started the replication from scratch and decided to use the root account to replicate and it solved the errors on the secondary side.
However when unlocking the ZPOOL on the primary I kept getting this:
Aug 12 12:48:08 nas uwsgi: [middleware.notifier:2975] Importing OneDrive  failed with: cannot mount '/mnt/OneDrive/Backup/Storage/Music': failed to create mountpoint
Refreshing the GUI would show all the datasets mounted and working, I had to restart the sharing services for them to work. The replicated data was not mounted however replication was working.
This was annoyingly very simple. The secondary server has two datasets called RBS-POOL/Storage/Music & RBS-POOL/Storage/Photos. I only replicated Music and Photos and not the parent Storage. Once I replicated the parent then it replicated the mount points on the other side.
The data is now readable on both sides.