InfoPath Dev

Dear All, I have published 2 InfoPath 2013 forms to Sharepoint 2013 document libraries. but after couple of days one of the forms started showing the error:

"There has been an error while loading the form. Click Try again to attempt to load the form again. If this error persists, contact the support team for the Web site. "

I made some testing:
1- publishing other forms to the same site and everything is fine.
2- publishing it again to a different document library but same error shows.
3- publishing it to a different document library in a different site and its working fine.
4- the form works fine in Infopath filler

any ideas? thanks

I rechecked all the connection inside the form and its working now.

because my second form is reading data from the first form so after some modification on first form, the second form could not load. after refreshing all the connection it worked.