ContentModule-built.js returns HTTP error 500

My Neos setup runs behind a NGINX HTTPS proxy. The traffic between my server and the loadbalancer is HTTP-only and NGINX does the SSL termination. Since Neos produces HTTP but no HTTPS URLs in this case I manually rewrite them with Apache’s mod_substitute on the origin server. So far so good.

Everything works as expected except the Neos backend. It simply does not load. seems to be the culprit.

Although it is a static file the server returns: Application Error. The Flow application could not be launched.

How can I get Neos to work?

Could it be that in that setup something goes wrong with your rewrite? First check if the file is actually there (it should be), then make sure the URL is actually accessible ON the application server. Also there are better ways than rewriting the URLs via apache. You can set a baseURL or use proxy headers to make Neos generate the correct URLs.

Thank you for your fast reply. I finally found my mistake. The apache module mod_substitute has a limit for the maximum line length and this was set to a pretty low threshold. I increased this to a higer value of 10m and it worked.

Sounds good. Which headers are used to determine the protocol?

Now, I’d like to see this in the official manual. What would be the right chapter for this?