I opened a table and focused some data row. Then I created a new sql and did a few queries, one of them deleted a row in the table I've previously opened. But I didn't notice it. Then I returned to the opened table and edited the focused row (the one that was already deleted actually) and I got very generic error message, something like "An error has occurred during update operation". I spent a minute to understand that this is a concurrency exception because I've deleted a row I wanted to edit.