To resolve this behavior, check out the form document before you change the form. To do this, locate the form document in the form library, and then click
Check Out in the list next to the document.
If you are not sure whether the document must be checked out, you should open the dropdown menu for the form and then click
Edit in Microsoft InfoPath to open the form. If check-out is required, InfoPath returns the following message:
You must check out this item before making changes. Do you want to check out this item now?