“404 FILE NOT FOUND” when attempting to open a new form or existing form

Issue:

When you try to open/edit/add a new form item, you encounter a “404 FILE NOT FOUND” error.

Resolution:

This issue might occur when someone alters field definitions of the SharePoint list that Sintel Forms are using.

To solve it, open the list, launch the Sintel Forms Designer and once it loads click on “Save and exit”. This should refresh the form configuration and resolve the issue.