When attempting to open a form after an item was submitted, the follow error occurs: An embedded page at formso365.nintex.com - An error occurred during an Ajax call.
Find either the current GUID of the form, or the list GUID (ID)
Navigate to https://SiteURL/NintexFormXML/
Identify the form xml here that is associated with your list.
These items use the naming structure `FormID_ListID` (edited)
Click the ellipses by the form associated with the list and select version history.
Restore the previous version of the form (Note: you may need to roll back further versions if multiple versions of the XML are corrupt).
Navigate back to the list where the issue occurred.
Open the forms designer to ensure the issue is resolved.
An embedded page at formso365.nintex.com - An error occurred during an Ajax call.
The root cause of this issue is currently unknown. The reason for the AJAX error is due to the XML located in the NintexFormXML library being corrupted at some point during the publishing process. This results in the XML being incomplete in the library, generating the error. Rolling back the version will resolve the issue of being unable to load the form but any changes that were made between the current and previous version will be lost. Those changes will need to be reconfigured.