TSM: ANR8985E The drive xxx in library xxx is using an encryption method that is incompatible with the current server settings.

I have faced confusing error message:

ANR8985E The drive xxx in library xxx is using an encryption method that is incompatible with the current server settings.

The root case of error was that I defined device class explicitly with parameter DRIVEEncryption and value OFF.
There was impact even I did not use encryption on library and its drives.

Drive was encryption capable but not enabled on library:
[root@tsm1 ITDT]# ./itdt -f /dev/IBMtape0 encryption
Getting drive encryption settings...
Encryption settings:

  Drive Encryption Capable... Yes
  Encryption Method.......... Library
  Encryption State........... NA
Exit with code: 0


So I changed DRIVEEncryption to ALLOW (default) even I did not use encryption and error message disappeared and volume got mounted...

define devclass IBMTAPE01WORM LIBRary=IBMTAPE01 DEVTYPE=LTO FORMAT=ULTRIUM8C WORM=YES MOUNTLimit=DRIVES DRIVEEncryption=ALLOW LBProtect=READWrite