Replication cannot send. Invalid argument

This morning I see an error I’ve never come across before. This replication has been running for over a year, so configs are good. It replicates from main to backup. All other replications to the same machine are fine, just this one throwing a cryptic “invalid argument’ error for some reason.

[EFAULT] send from @auto-2026-03-10_03-10 to TANK/POOL@auto-2026-03-11_03-10 estimated size is 624B total estimated size is 624B warning: cannot send 'TANK/POOL@auto-2026-03-11_03-10': Invalid argument.

The plot thickens.. If there are errors in all of these snapshots, how come I was just notified this morning? Did they all get corrupted overnight? Also, no errors or corrupt snapshots on the backup server. The data itself appears to be fine as I ran find /mnt/TANK/POOL -type f | wc -l and got no errors.

I deleted the corrupt snapshots and resync’d without error. Still not sure what actually happened. Thoughts?

pool: TANK
 state: ONLINE
status: One or more devices has experienced an error resulting in data
        corruption.  Applications may be affected.
action: Restore the file in question if possible.  Otherwise restore the
        entire pool from backup.
   see: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-8A
  scan: scrub repaired 0B in 11:17:24 with 0 errors on Mon Mar  2 11:16:26 2026
config:

        NAME                                      STATE     READ WRITE CKSUM
        TANK                                      ONLINE       0     0     0
          mirror-0                                ONLINE       0     0     0
            b7d41040-4b21-4ad3-a355-3da496af0aab  ONLINE       0     0     0
            6f1fe9bf-0308-4e02-b816-7447d489c87c  ONLINE       0     0     0
          mirror-1                                ONLINE       0     0     0
            040ea455-3720-4ea1-b057-18b0e41236e7  ONLINE       0     0     0
            da8ce55c-cc90-492f-8372-b7d2ec2c060b  ONLINE       0     0     0

errors: Permanent errors have been detected in the following files:

        TANK/POOL@auto-2026-03-11_03-10:<0x1>
        TANK/POOL:<0x1>
        TANK/POOL@auto-2026-02-26_03-10:<0x1>
        TANK/POOL@auto-2026-03-01_03-10:<0x1>
        TANK/POOL@auto-2026-03-02_03-10:<0x1>
        TANK/POOL@auto-2026-03-06_03-10:<0x1>
        TANK/POOL@auto-2026-03-10_03-10:<0x1>
        TANK/POOL@auto-2026-03-09_03-10:<0x1>
        TANK/POOL@auto-2026-03-08_03-10:<0x1>
        TANK/POOL@auto-2026-03-04_03-10:<0x1>
        TANK/POOL@auto-2026-03-05_03-10:<0x1>
        TANK/POOL@auto-2026-02-28_03-10:<0x1>
        TANK/POOL@auto-2026-02-27_03-10:<0x1>
        TANK/POOL@auto-2026-03-03_03-10:<0x1>
        TANK/POOL@auto-2026-03-07_03-10:<0x1>