Is it possible to replace or redesign Infopath forms for XML document library in SPO ?
It throws error when i try to create the form in Nintex form .
Or do i need to create a list and handle all the variables in the Nintex form ?
Please suggest what approach shall i go with.
You cannot create a Nintex Form on Forms library. Instead, create a SharePoint list and craete a Nintex Form. Then you can create variables, rules, also use can have many runtime functions.
its very difficult to achieve all the similar functionalities from old Infopath 2010 in Nintex form .
I hope its get better in future