Apache 2.4.7 throws error 502 when uWSGI returns 401 with mod_uwsgi_proxy

[islavov]

Using mod_uwsgi_proxy, I start getting error 502 and I can clearly see that uWSGI returned 401.
This starts to occur after a couple of successfully returned 401 responses. After that, no 401 reaches the web browser. I get this from apache.

The proxy server received an invalid response from an upstream server.

I use this in my apache conf
ProxyPass /pyresp uwsgi://127.0.0.1:3051/ timeout=600

And this is my uwsgi conf

[uwsgi]
env = HOME=/home/ubuntu
socket = 127.0.0.1:3051
chdir = /home/ubuntu
module = pyrespweb.web:app
pythonpath = /home/ubuntu/pyresp
master=True
processes = 4
buffer-size=32768
venv = /home/ubuntu/.virtualenvs/pyresp
uid = ubuntu
gid = ubuntu

Nothing special as you can see

I will be happy to provide as much info as needed, but currently I have no what to look for.
This issues is not observed with mod_uwsgi.

[unbit]

You mean that when your app returns 401, Apache returns 502 for those requests ? Or it start returning 502 for every kind of request after a bunch of 401 ?

[islavov]

After a bunch of requests, it starts returning 502 only for 401s. Other requests are fine.

[unbit]

Ok, and nothing in apache error log ?

[islavov]

Nothing related.

[unbit]

Can you check if using mod_proxy_http + --http-socket instead of mod_proxy_uwsgi + --socket has the same behaviour ?

Thanks