These files failed to back up

I have read the help documents and done what I believe they said to do. I still have files with the following extensions that do not back up: .doc, .pdf, .accdb, .xlsx. Many other documents with those extensions are in the WD backup.swstor file on my EasyStore external drive. There are others that are not backed up but I am not concerned about them. What do I need to do?

There may be some issue due to which these files are not backing up,

You should check the permissions and rights to folders and files which are going to backed up. Ensure that files must not be password protected or locked and have permissions to access the files.

Also, you need to check whether the files were in use during the backup process or not.

These are my files on my computer and created by me. They were not as far as I can tell not in use. What else do you suggest?Thanks.