After a deeper search online, some things came up to check.
1. How big is the DB (either monolithic OR the file that contains the tables if it is a split DB)? Some reports suggest that the tables in question were reaching the size limit.
2. Is a sub-form involved? If so, verify that the sub-form's parent & child links actually represent a field that is on the appropriate form. Some reports suggest that the field named as a link doesn't exist on the form it represents.
3. Is it possible that the sub-form link field sometimes contains a NULL? Some reports suggest that - particularly when multiple sub-forms are involved, if one of them is a null, the problem crops up but goes away if you just click OK on the error.
I'm seeing references to this exact error as far back as 2001 - which has to be Access 9.0 (Ac2K) or earlier. I'm also seeing the error reported in 2005, 2007, and 2012, no idea of which versions in each case.
I have to say that I'm really surprised that this error is still around.
@CedarTree - You also reported this error in July of 2022, so whatever it was hasn't gone away. However, the fact that I can find references over 20 years old means it isn't a SharePoint thing because that wasn't around then. What version of Access are you running now and which version would you have been running in 2022?
