Hey @tomm,
Just a guess here: I'm assuming you're using retool's database, right? I've had this happened to me whenever I did any changes to the column or to the table, and so I needed to reset the primary id's sequence,
Here's a post that may be of guidance.
A way of knowing if this is what causes the issue, just go to the table you're trying to add a row and try manually adding a row, it may throw an error like this:
