---
title: "Google AppEngine – Python – issubclass() arg 1 must be a class"
description: "<p>If you are getting the error “”issubclass() arg 1 must be a class”” with Google App Engine SDK for Python on Linux its probably because you are running Python 2.6 (and will probably happen to you when you run Ubuntu 9.04 – 2.6 is the default there).</p>
<p>Just run the dev server under python 2.5 (i.e. python2.5 dev_appserver.py)</p>"
doc_version: "1"
last_updated: "2017-06-02"
date: 2009-09-14
tags: [GAE, Google App Engine, Google AppEngine, Linux, Python, Python 2.6, SDK, Ubuntu]
canonical: "https://eran.sandler.co.il/2009/09/14/google-appengine-python-issubclass-arg-1-must-be-a-class/"
---

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If you are getting the error &#8220;&#8221;issubclass() arg 1 must be a class&#8221;&#8221; with Google App Engine SDK for Python on Linux its probably because you are running Python 2.6 (and will probably happen to you when you run Ubuntu 9.04 &#8211; 2.6 is the default there).

Just run the dev server under python 2.5 (i.e. python2.5 dev_appserver.py)