Hardware encryption doesn't work on tape operations after update to 9.5 Patch 4b

After you update to patch 4b (9.5.4.2866), you may face the following encryption-related issues during the backup and restore procedures.
Restore from tape backups made in the previous product versions with enabled hardware encryption may fail with the following error message:

[11.07.2019 20:07:56] <  5652> mt |   Drive encryption status:
[11.07.2019 20:07:56] <  5652> mt |   Encryption Mode: Disabled
[11.07.2019 20:07:56] <  5652> mt |   Decryption Mode: Disabled
[11.07.2019 20:07:56] <  5652> mt |   Raw Decryption Mode Disabled (RDMD): Disabled
[11.07.2019 20:07:56] <  5652> mt |   Volume Contains Encrypted Logical Blocks (VCELB): Disabled
[11.07.2019 20:07:56] <  5652> mt |   Logical Block encryption parameters: Application Managed
[11.07.2019 20:07:56] <  5652> mt |   Hardware encryption is available
[11.07.2019 20:07:56] <  5652> mt | ERR | [MT]SCSI PASS THROUGH DIRECT ended with Scsi Error Fixed format, current;  Sense key: Illegal Request. Additional sense: Invalid field in command information unit
[11.07.2019 20:07:56] <  5652> mt | >>  |tr:Failed to enable hardware encryption, tapeHandle: 0x00000000000006a4
[11.07.2019 20:07:56] <  5652> mt | >>  |tr:Failed to create TapeReader.
[11.07.2019 20:07:56] <  5652> mt | >>  |tr:Failed to create TapeFileReader, setPba: 614675, localFla: 136589546, restFileSize: 4621392384
[11.07.2019 20:07:56] <  5652> mt | >>  |An exception was thrown from thread [5652].

Tape backups will finish without any visible errors. However, the tape job statistics may show that the software encryption was used instead of the hardware one.

This issue occurs under the following conditions:
 

1. The tape library is hardware.
2. Encryption is enabled in the target media pool settings (https://helpcenter.veeam.com/docs/backup/vsphere/add_media_pool_encryption.html?ver=95u4).
3. In the tape library settings, the encryption is set to Application managed (this setting is configured on the vendor side).

To solve the issue, apply the hotfix:

1. Download the hotfix.
2. Check the current version of Veeam Backup & Replication. It must be 9.5.4.2866.
3. Make sure that no jobs are running, close the console, and stop all Veeam services.
4. Right-click on the installation file and click "Run as administrator"
5. Go through the wizard to install private fix.
6. Relaunch Veeam Backup Console and let Veeam automatically update hosts added to the Veeam server.

DOWNLOAD PRIVATE FIX

MD5 for kb2981.zip: 567db99e79fb6bd95251deb769d90238
SHA-1 for kb2981.zip: 0c8ad6b3c0841402c8da1e05e1acbb7e0bfcadf8