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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Exception in finalizer of custom encoder","articleBody":"### Environment\r\n\r\n-   Pythonnet version: master\r\n-   Python version: 3.7\r\n-   Operating System: Windows 10\r\n\r\n### Details\r\n\r\nI am using a custom encoder defined in Python to work around the conversion of IList to Python lists (see https://github.com/pythonnet/pythonnet/pull/963#issuecomment-642938541):\r\n\r\n```python\r\n# Prevent Python.NET from converting IList to Python lists\r\nfrom Python.Runtime import PyObjectConversions\r\nfrom Python.Runtime.Codecs import RawProxyEncoder\r\nclass  ListAsRawEncoder(RawProxyEncoder):\r\n  __namespace__ = 'Python.Runtime.Codecs'\r\n  def CanEncode(self, clr_type):\r\n    return clr_type.Name == 'IList`1' and clr_type.Namespace == 'System.Collections.Generic'\r\n\r\nlist_encoder = ListAsRawEncoder()\r\nPyObjectConversions.RegisterEncoder(list_encoder)\r\n```\r\n\r\nThis works fine until I have called `Python.Runtime.PythonEngine.Shutdown`, and GC kicks in. Then there is this exception:\r\n```\r\nUnhandled exception\r\nException thrown:\r\nSystem.InvalidOperationException: Handle is not initialized.\r\n   at System.Runtime.InteropServices.GCHandle.Free()\r\n   at Python.Runtime.PythonDerivedType.Finalize(IPythonDerivedType obj)\r\n   at Python.Runtime.Codecs.ListAsRawEncoder.Finalize()\r\n```\r\n\r\nThe crash started happening after #958 was merged.","author":{"url":"https://github.com/danabr","@type":"Person","name":"danabr"},"datePublished":"2020-10-12T08:39:43.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":7},"url":"https://github.com/1256/pythonnet/issues/1256"}