I am working with a lot of imports to get legacy data into a relatively new set up.
Most common problem I have had with imports is a “required” field column of data that is not correctly populated. Specifically, I had errors in the “ID”(2nd column in xlsx files) if they weren’t quoted properly and/or the name-series didn’t match.
From there, make sure that the UOMs match. It probably depends on what doctype you’re importing, so maybe mention that if it still fails once you’ve checked.
I found that the best way is to input one dummy record, then export with data, and us the resulting xlsx file to feed data back (erase the dummy row when you do this)
Hope this helps