Trying to remove fragment from view gives me NullPointerException on mNextAnim

Solution 1:

I know you've solved this yourself, but I want to explain how this error happens, since it just happened to me.

Basically you're calling hide(), remove(), etc., with a null value.

The error isn't obvious, and the stack trace doesn't originate from your own sources when this happens, so it's not trivial to realise what it is.

Solution 2:

It also happens when you call FragmentManager.popBackstack() without there being a fragment in the backstack.

Solution 3:

this is because you add or show or hide a fragment which is null now,try to check if it is null ,before you use it!

Solution 4:

My problem was that FragmentManager's getFragments() sometimes returns a list where some fragments are null, and I was removing those null fragments.