What happens when you hit the SQL Server Express 4GB / 10GB limit?

Question

What kind of error occurs? What do users experience? Can you access the database using tools and what if you get it back under the 4GB / 10GB limit?

Answer 1

Actions that increase the size will fail, e.g Insert, Update. You will still be able to access the database and run maintenance on it to bring the size back down.

I would setup some maintenance jobs to alert you before the database reaches this size so you can prevent any data being lost.