Backup reproducibly fails with 'Exception from server: The size of the internal FIB block cannot be less then the default block size'

Since a few weeks, my backup of my Windows disk (that used to work seamlessly) fails with:

Error: Shared memory connection was closed. Failed to upload disk. Skipped arguments: [EmulatedDiskSpec>]; Agent failed to process method {DataTransfer.SyncDisk}. Exception from server: The size of the internal FIB block (58368) cannot be less then the default block size (1048576). Failed to download disk 'a289c469-b376-11ec-83e5-68545a920099'

I could not find this particular error message online. How can I get it to work again?

I use Veeam Agent for Windows 6.2.0.121.