In fact, I'll add general advice on that topic. No matter WHAT you intended to do, if you are going to be making ANY changes to a shared back end file, you have to take the app offline in one of several ways so that nobody can be in it. Then make a WINDOWS-level manual copy of the file as a backup. (Don't use Access for this first copy.)
Make your changes, manually do a compact and repair, and then perhaps make a backup copy using the Access File >> Save options to make a backup. Then and ONLY then, put your app back online.
Now, as to making the app go offline: What I always did was look at the lock file. If there is no lock file, then the odds are that nobody is using the file. Make the non-Access backup copy to another folder. Now rename the shared-folder's copy of the file to anything else. If you can't rename it, the file is still open. BUT if you rename it successfully, nobody will be able to open the front-end file because it won't find the back end.
Now make a copy of the file to a local folder, rename the local copy back to .MDB or .ACCDB as appropriate, make your updates, etc. Open it and do a COMPACT & REPAIR. Now make a backup copy. That copy will have a date tag added to the name. Now finally, copy the local file back to the shared folder (with the proper name).
At this point you can dump the renamed copy of the file from the shared folder because you have three other backups in three different places. Dispose of them as your business model sees fit.