InfoPath Dev

I have a simple form I just updated to FormsViewer. When I upload the FV version to Manage Templates and update the Web Part with the JS file, the form works fine for creating a new one and viewing new (FV-created) requests; however, the existing requests produce this message "Error - An unexpected error occurred. Please contact technical support. The form will now close. OK" It is a simple form that displays reports after a user verifies their credentials and acceptance of an NDA, and has very light usage, but I imagine some day, InfoPath Web forms will no longer work in SharePoint 2013 (On Prem). For now, I can leave it as it is, but if/when forced to use with FormsViewer, I will not be able to view the historical requests. Any ideas on what is happening?

How is your form library set up for opening existing forms? are you using the .JS script for classic views, or FormsViewer extensions? It seems to me like the issue may be there - that the URL being opened is incorrect somehow.

It is set up with the .JS file. Don't know what changed, but I retried setting it up again this morning and now it works. I'll chock it up to SharePoint just messing with me. Thank you for your response.