<div dir="ltr"><div>My Buildbot 0.9.5 server randomly crashed today, with twistd.log showing:<br><br>2017-05-16 21:00:19+0000 [-] Unhandled Error<br>    Traceback (most recent call last):<br>      File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/twisted/internet/defer.py", line 1030, in _cbDeferred<br>        self.callback(self.resultList)<br>      File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/twisted/internet/defer.py", line 457, in callback<br>        self._startRunCallbacks(result)<br>      File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/twisted/internet/defer.py", line 565, in _startRunCallbacks<br>        self._runCallbacks()<br>      File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/twisted/internet/defer.py", line 651, in _runCallbacks<br>        current.result = callback(current.result, *args, **kw)<br>    --- <exception caught here> ---<br>      File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/twisted/internet/base.py", line 433, in _continueFiring<br>        callable(*args, **kwargs)<br>      File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/txrequests/sessions.py", line 46, in <lambda><br>        reactor.addSystemEventTrigger("after", "shutdown", lambda: pool.stop())<br>      File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/twisted/python/threadpool.py", line 274, in stop<br>        self._team.quit()<br>      File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/twisted/_threads/_team.py", line 226, in quit<br>        self._quit.set()<br>      File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/twisted/_threads/_convenience.py", line 35, in set<br>        self.check()<br>      File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/twisted/_threads/_convenience.py", line 46, in check<br>        raise AlreadyQuit()<br>    twisted._threads._ithreads.AlreadyQuit: <br><br></div>What is the cause of this?<br></div>