KB #1003: "XX finished with warning: Failed to backup item: XXX, Item may have a virus reported by the virus scanner plug-in"

Challenge

Backup job may return the following warnings

OneDrive "X" finished with warning: Failed to backup item: "X", Item may have a virus reported by the virus scanner plug-in

SharePoint "X" finished with warning: Failed to backup item: "X", Item may have a virus reported by the virus scanner plug-in

Solution

Remove the file/Remove the virus with anti-virus software.

Cause

This is the internal anti-virus plugin within Microsoft 365 that has detected some data with containing a virus. When detected, Microsoft moves the file to quarantine, not accesible for backup.