Error: Failed to perform patch of the full backup

could you please provide any logs? 

Thanks for reaching out ​@makacmar. Please see if this helps. Logs attached. 

25.04.2025 01:25:36.946]    <84>    Info (4)    Merging oldest incremental backup into full backup file (41% done)
[25.04.2025 01:25:38.538]    <85>    Info (4)            [AP] (42867c21) output: <VCPCommandResult result="false" exception="Agent: Failed to process method {Transform.Patch}: An unexpected network error occurred.&#x0A;Asynchronous request operation has failed. [requestsize = 233472] [offset = 10878500864]&#x0A;--tr:Error code: 0x0000003b&#x0A;--tr:Failed to read content&#x0A;--tr:Failed to process de-duplicated block&#x0A;--tr:Failed to write block to blocks store.&#x0A;--tr:Failed to replace FIB block. FIB index: [106029]. FIB: [FS3.vhdx].&#x0A;--tr:Failed to process area [Data block. Start offset: [111179464704], Length: [1048576], Area ID: [27284].].&#x0A;--tr:Failed to patch file [FS3.vhdx]. Is full restore: [false].&#x0A;--tr:Failed to perform patch of the full backup [veeamfs:a:9f56bbd7-bb29-4e0b-b236-75ec3f3e287c (4b8a2d1d-f7ff-4b7b-942a-2183c83ec790)/Scsi0-0\FS3.vhdx@\\192.168.4.253\FS3 Remote copy\FS3 Offsite Copy\FS3 Backup\FS3.4b8a2d1d-f7ff-4b7b-942a-2183c83ec790D2025-04-03T030009_3A2E.vbk] with [1] patch layers. Rollback: []." />
 

can you run full copy job?

Sure, I can run and update how it completes.

Also when posting try to add things like VBR version, configurations, etc. as it helps as well with assisting.  We are also not tech support so we give our best answers to help.

The full backup too failed with errors. Attaching logs for further investigations. 
The VBR is version 12.3.1.1139. Appreciate the help being provided. 

Please create a support ticket with Veeam as the community is not a support site. We offer suggestions and tips.  It seems like support is the best direction here to resolve this.

You may have an orphaned backup file that failed to merge into the full backup if you also run incrementals.

Have a look at your backup repository and check if any files stand out. 

Another option is to try a full backup into a new location and see if the error appears again, but watch out for your retention period as the backups in the old location will no longer be managed.

• "Unexpected network error" → network issue (could be instability, disconnection, or timeout between the backup repository and the server).

output: <VCPCommandResult result="false" exception="Agent: Failed to process method {Transform.Patch}: An unexpected network error occurred.&#x0A;Asynchronous request operation has failed. [requestsize = 233472] [offset = 10878500864]&#x0A;-

• Error 0x0000003b → usually in Windows it is related to a System Service Exception, which can occur due to driver issues, hardware failures, or in cases like Veeam, network or disk I/O problems.

Error code: 0x0000003b
--

• "Failed to read content" + "Failed to write block" → indicates a read or write failure during the merge process (consolidation of the incremental backup into the full backup file).

tr:Error code: 0x0000003b
--tr:Failed to read content
--tr:Failed to process de-duplicated block
--tr:Failed to write block to blocks store.
--tr:Failed to replace FIB block. FIB index: [106029]. FIB: [FS3.vhdx].
--

The logs indicate that the Backup Copy Job attempted to build tasks but found no available source backups to process. This may happen if the source backup session failed, the restore points have expired, or the backup files are missing or corrupted. It is recommended to verify the health of the primary backup job and ensure the restore points are accessible. Also, you can try to using veeam validator on the primary job to check the file integrity.

However, at this point, it is recommended to open a support ticket with Veeam for a deeper investigation.

from my experience next suggest form support is: another try is to run copy job over new copy job or forget backups from configuration database and try to run to isolate if the problem is with secondary repository/vbm files, ….

next option is to run healtcheck on primary job  as mentioned above