If you - like me on tech-blogger.net and routerzwang.de - use the Nginx-Pagespeed module, you should keep it up to date. That way you can save yourself a lot of troubleshooting.
If you're going to be Nginx self compiledand uses the module "ngx_pagespeed", you not only have to keep Nginx up to date, which in the last versions brought HTTP/2 support, but also the corresponding modules. After neglecting this for a while, I could not log into the WordPress backend anymore. The necessary troubleshooting should be spared others, so here are the main steps:
cd NPS_VERSION=<span style="color: #ff0000;">1.9.32.10</span> wget https://github.com/pagespeed/ngx_pagespeed/archive/release-${NPS_VERSION}-beta.zip unzip release-${NPS_VERSION}-beta.zip cd ngx_pagespeed-release-${NPS_VERSION}-beta/ wget https://dl.google.com/dl/page-speed/psol/${NPS_VERSION}.tar.gz tar -xzvf ${NPS_VERSION}.tar.gz
You get the latest version directly at Google, on 11/29/2015 this was version 1.9.32.10-beta. After you have done the above steps, you can install Nginx "regular", but you have to make sure during configuration that the new version of the ngx_pagespeed module is also used.
So if you have unexplainable problems with your website and use Nginx 1.9.x with ngx_pagespeed, you should - as with any software - make sure that you are using the latest version. This can be easily achieved by following the simple installation steps.