A family of Microsoft relational database management systems designed for ease of use.
Starting 1 year ago I have had the same problem on several sites with the same database schema. In all cases the database sizes were around 1.2G. Repair was simple - opening with the full version of access auto fixed the "corruption". But "corruption" kept happening with users getting the "Unrecognized format" error reported. After trying everything else I suspected that for this particular database, the size was triggering the error (I know that the max size is 2G and on the same computers there are several other databases being accessed simultaneously that are much larger than 1.2G that do not corrupt. Some of them are 1.8G with no problem. The only difference is they have less complex schema than the one that corrupts.)
As soon as I cull enough records to get the databases below 1.2 gig, say 800MBytes, the problem goes away. Not ideal to have to cull records but the customer is at their wit's end with the disruption. Over time when the size creeps back up to 1.2G the same corruption happens again and again.
So in some cases where the schema of a database is above a certain complexity, the database size limit seems to have reverted to be around 1.2GBytes. All the errors are the same as those encountered when the size exceeds 2G. I know the max size is supposed to be 2G and I have lots of sites with databases between 1.2 and 2G that have no problems. But this one specific database, with a complex schema, ALWAYS corrupts when the size gets to 1.2G and is always fixed by reducing size (unfortunately culling useful records).
After 10 years of no such problems this has started to happen in the past 12 months. It is not limited to Win10 - it happens on Win7 as well. Something has changed in the OS - whether the database is in .mdb or .accdb the problem is the same.
Has anyone else experienced this 1.2G size limit?