The ValueRule object belonging to.....

This frustrated me for about 20 minutes today before I discovered the cause...

Owner : The ValueRule object belonging to the TextFieldDef
'Change.Owner' does not have a name.

Every time I went to commit I got this error. I had made some changes
to the field but no end of changing Validation settings, Autofill
Rules, Calculations would solve the issue.

Here is an explanation of how to solve this issue if you come across.
The change I had made to the field was as follows:-
1. The field had a default value from a function "Current Login ID"
2. I selected Simple Value and left the value blank.

The issue is the field still references a function in the background.
(hence the "ValueRule object" Not having a value)

When removing a function from a Default there is an option in the
function drop down list of "None".

This will remove this error.