Azure backup - Backup completed with warnings

Good morning,
I activated a backup in azure for a pc.
Today I get a notification of “backup completed with warning” and it instructs me to check this link “http://go.microsoft.com/fwlink/?LinkId=816510” for troubleshooting.
Going to that page it only indicates to me that some locked files that fail to upload to the server.
Could someone point me to some solutions?
Thank you very much