I have been testing various features and functionally of a  recent SharePoint 2010 to SharePoint 2013 upgrade I preformed. When I encountered an issue involving a list item used heavily buy one of my departments.

The issue presented itself when the users attempted to create new work items and this is when SharePoint 2013 displayed an informative error messages telling me something went wrong.

I was able to obtain the correlation ID,

and after some filtering and digging in the ULS  (Unified Logging System) I was able to see that this list was created using InfoPath.

After seeking additional information from a few developers it was suggested that this form may need to be recreated. I was later to find out that other customer shave been facing issues with InfoPath and SharePoint 2013 forms.

The Office Team @ Microsoft has released a statement via their Blog that they are “evolving  forms technology” in an effort to streamline and deliver a more integrated  user experience.

In their own words:  “we’re retiring InfoPath and investing in new forms technology across SharePoint, Access, and Word. This means that InfoPath 2013 is the last release of the desktop client, and InfoPath Forms Services in SharePoint Server 2013 is the last release of InfoPath Forms Services.” 

I am taking that means the older forms used from back in Office SharePoint Server 2007 have been deprecated, eventually the rest.

That said here is a link to their blog post:
Update on InfoPath and SharePoint Forms