I have been debugging why my tabular form in Apex 5.2 enters an error page http://servername/ords/wwv_floe.accept, containning
"Current tabular form data is too old; the source data has been modified.
Click here to discard your changes and reload the data from the database."
Surprisingly, when you have a custom defined validation rule PL/SQL Function body returning boolean) mixtured with some predefined rule, like "Item is not null". Whenever, a validation fail, the system will goes to this page, and some/all user input will lost. But if all validations are defined in the same way, either all using predefined rules, or all using custom defined rules, the application will not enter this page when there is avalidation fail. The error message will only show Inline in Notification.
Conclusion:
To avoid losing user input data on a tabular form, define all the validations using same method.
