There are a few possible reasons for an accdb to become read-only.
- You actually opened it in read-only mode.
- Close and reopen it making sure it's not in read-only mode.
- The accdb is stored in a location on a network to which you do not read/write/delete permissions and someone else has it open exclusively.
- Make sure you only open an accdb FE when it is on your own computer, not from a network location.
- The accdb was recently downloaded from an internet site and has had the MOWB added to it. Or, and this is more likely, it is marked as Read-Only because it was downloaded from somewhere.
- Check for those and resolve if appropriate.
- There is a problem with the link to the SharePoint Site and lists on it.
- Perhaps Access can't identify the Primary Key on the table (list) you are trying to update. Relink the SharePoint lists.
Trouble-shooting requires eliminating possible sources of a problem, one at a time.
There may be other problems beyond those, but eliminate them first. If that doesn't resolve the problem,