Relationship is not valid
Today I was running a routine script that involved deleting a found set and got an error message (and I'm not going to get this exactly right) that read "This operation could not be completed because the relationship between the two tables is not valid". I HAD done some work on the schema recently, and had obviously made a mistake. However, the "operation" involved the deletion of portal rows, and the relationship between the Layout Table and the Related Table was correct. The problem was with an incorrect relationship (in a different file as well) that was quite removed. My question to the error message is "Which two tables?" Although I only had to examine the tables whose relationships I had recently changed and found the rather simple problem immediately (almost) I shudder to think of how difficult it could have been. The error message should identify the Tables.
The error message should identify the specific tables in the invalid relationship.
No specification of tables involved.
I've encountered that myself and found myself asking "which relationship and which field is the key field?". Identifying the name of the TO involved would be a singificant time saver here.