Fatal Python error: deallocating None

[bwoods8]

When iterating over a 4000 list that is getting and creating principals. The following error occurs:

Fatal Python error: deallocating None
Aborted (core dumped)

I can see the reference count of None reduce if i print:

print(sys.getrefcount(None))

I tried iterating with the "getprinc" method and you can clearly see the refcount to None drop consistently...