Invalid Cast Exception was unHandled MySQL

Question

When I run the program I get this error:

Invalid Cast Exception was unHandled

This is part of form for fill a database, and visual

Answer 1

The problem is the ExecuteScalar that in MySql returns an Int64 not an Int32. So the invalid cast when you use an explicit cast

With a conversion your error should go away

 int UsuarioExiste = Convert.ToInt32(sqlCommand.ExecuteScalar());

You are not alone to fall in this problem

Of course everything that has been said in the answer from Mr Soner Gönül is still applicable and should be done ASAP.