The full text of the error is "EditRecord failed because the default alias represents a record which is read only."
This occurs when submitting the first Userform in a series of 6 forms - the first one generates a Serial Number, which is the Primary key for the table. The following forms add more data to that same Serial Number entry, and don't generate this error. The Serial Number is manually entered into the first form box and then written to the table when submitted. No custom code in this form at all, besides a BeforeInsert timestamp, but removing that code completely still generates the same error upon submission.
All of the form data still writes to the database upon form submission. Nothing is actually going wrong or misbehaving beside that error pop up.
Any suggestions?