I'm not sure this is a problem in cryptography, but I think it might be related.

Over the past few days, I've had problems with my Apache 2.4.23 server, where it failed to correctly serve HTML files from disk over HTTPS. Restarting it solves the problem temporarily.

This Apache installation makes use of mod_wsgi (with Python 2.7.10) to run a number of WSGI applications, some of which use cryptography. In the Apache error logs, I found a lot of messages like this:

extern "Python": function Cryptography_rand_bytes() called, but @ffi.def_extern() was not called in the current subinterpreter.  Returning 0.
extern "Python": function Cryptography_rand_status() called, but @ffi.def_extern() was not called in the current subinterpreter.  Returning 0.

I somewhat recently upgraded from cryptography 1.3.4 to 1.5.2, so this might be related.

Any suggestions on what might be wrong here?