[v1.8.8] PermissionError - OpenNumismat\Collection\Collection.py:970

OpenNumismat: 1.8.8
OS: Windows 10 (10.0.19041)
Python: 3.4.4 (32bit)
Qt: 5.5.1
Locale: en

Traceback (most recent call last):
File "OpenNumismat\Collection\Collection.py", line 970, in detachReference
PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'E:/OpenNumismat/reference.ref'