Hi David, you asked this recently ( https://599cd.com/blog/display-article.asp?ID=352&CommentID=77302#StartOfComments ), and the answers are still the same: there is no table limit, and the problem is due to invalid joins.  That error message is just what it says: you used an invalid outer join.  There are a number of situations where certain joins don't work but others do.  Maybe other posters could suggest the necessary videos, because this topic requires some good understanding.  The short version of it is that you can't have an outer join point towards an inner join, and you can't have two outer joins point towards the same table.  See this short video from Microsoft:  https://support.microsoft.com/en-au/office/video-fix-the-ambiguous-outer-join-error-c36948dc-c481-48c6-809d-38427e9ffdd7

Thanks, I thought I asked this question in a different forum. I will look at the video, but I just realized that one of my problems may using a query (to concatenate the names of my clients) as a combo box record source. which why I am also coming up with blank columns when I create queries from tables. I went back to using the source table with better results. That said, it would be helpful if Access could concatenate names in a table.