SOLUTION: FRM-40202 - Required Field must be entered error
I was having a problem querying Oracle using a non-database item. I was using an LOV to get an employee ID and then a button that would return query results. I kept getting error FRM-40202. I looked it up on the internet and on METALINK but found only a couple of suggested solutions - none of which would work for me.
Then I went into the property palette of the form itself and discovered that by changing the Validation Unit property (located under the Database category) from Default to Form, I would no longer get the message. So in other words, the message was popping up because the application was validating data each time control moved away from the first field on the form.
Don't know if this will apply to everyone's case but it is certainly another option to try if you are repeatedly getting this error message.