The process cannot access the file because it is being used by another process

Linux:

There are utilities that can be used to determine File Locks on a Linux repository, and this section will cover the usage of lslocks. However, there may be other distribution-specific utilities and methods. It is critical to differentiate between Locked and Opened files. It is possible for a file to be in a locked state but not be actively opened. A command like lsof will only list actively opened files.

• LSLOCKS — Requires util-linux package
• LSOF — LSOF used without any options will show a list of all open files belonging to active processes. Specifying a particular file will show active processes for that file. If the file name is known using the following:
  

  lsof “\path\to\file”
  

Manually investigating /proc/locks can also be done like so:

sudo find -L /proc/*/fd -maxdepth 1 -print -exec readlink {} \;

In either scenario, one must verify that the file is not actively modified. File Locks can come from a variety of sources. If a job is unexpectedly terminated due to a network drop, it is plausible that the Veeam Agent finished but never received a terminate command. If the repository uses deduplication, the storage may have too aggressive of a profile active and is locking the file(s) as soon as Veeam releases a lock on them.

Once verified that the locked file is no longer being modified, it is safe to manually kill any process still maintaining a lock on the file.

Killing a process that is modifying a file may result in a corrupted file.