Custom error messages

Is there a way to create a custom error message?

I have a simple Pickaxe form in a studio. When I tested it, some people thought they could enter text in the submit box, and they got the following error message (“Please paste a valid website/video link or drag a file to add to the knowledge base.”):

Im not using video at all, just text files. Is it possible to create custom messages @admin_mike ?

It is not possible to customize this specific error message.