Are they the exact same version of Access? One isnt using 365 which might auto update and another using 2019?

Assuming you've tried this?

https://docs.microsoft.com/en-us/office/troubleshoot/access/database-requires-newer-access

Also looking around it appears that it's possible to be stuck on the older version of access. From reddit:

Can you directly open the database (instead of connecting to it)? If you can, follow this note

You can determine a database's file format version by pressing Ctrl-G to open the Immediate window. Type ?Application.CurrentDB.Version in the window, and then press Enter. The use of a Large Number data type sets the file format to version 16.7.

Just some ideas.

Yes, exact same desktop version.  No 365 involved (ever).  I researched this for days before posting.  Others have had this error message and it seems to be the Sasquatch of the access community - only fuzzy pictures with ambiguous explanations that lead nowhere.  I am now going to backwards de-construct my database in an effort to find the "feature" where it started this mess.  I added some buttons as Richard did in Access Beginner 7, Video 5 at 8:56 seconds.  I like that overlapping invisible button feature (so cool!).  We'll see if that was the culprit.  Many thanks.  Determined in Colorado.

That's weird. I have not come across this one yet. Try creating a new, blank database on the PC that gives you the error message. Import the objects from the database. See if it works. If not, try importing the objects one at a time until it doesn't work. That will tell you what form/report/module is causing the problem. I'm assuming you've run down the rest of the troubleshooter.

I did find the article in BigInt but honestly didn't think it applied because I'm not using any big numbers.  Just simple forms and such.  I did follow the steps and the version number came back 32.0.  (screen capture follows)  Sooo, again I'm not sure if 32 versus 16.7 is good or not.  I am heading off to work to run the version number on the computer at work.  Thank you for helping.  You and Richard are great.  Cheers to you both.

I see your problem. Date/Time Extended is new. Change it to Date/Time. You shouldn't need that.

YOU ARE THE MAN !!!!  Thanks to you and Alex for your help.  You saved the project!.  Changed away from extended to just Date/Time.  Cannot thank you guys enough.  Salute to you gentlemen.

You are welcome. Never would have seen it without your screen shot. So glad I added that to the site. :)