I have a very weird problem with PHP FPM in combination with Apache and mod_fastcgi. Whenever a PHP file is requested, Apache adds Content-Language: de to the response headers. For the life of me, I cannot figure out why this is happening! I'm using Ubuntu 16.04, my Apache version is 2.4.18. My PHP FPM is a custom build. I'm using the following config to process PHP files:
<FilesMatch ".+\.php$"> SetHandler php-fcgi </FilesMatch> Action php-fcgi /php-fcgi Alias /php-fcgi /foo.fcgi FastCgiExternalServer /foo.fcgi -socket /bar.sock -pass-header Authorization The following Apache modules are enabled: actions, alias, autoindex, dir, env, fastcgi, filter, headers, mime, negotiation and setenvif.
The module configs are left untouched. There is no DefaultLanguage set as far as I can see.
Any idea where the header is coming from and how I can remove it?
EDIT
When requesting a plain .html file, the following headers are sent: Date, Server, Connection, Keep-Alive, ETag.
When requesting a PHP file with <?php exit('Hello World');, the following headers are sent: Date, Server, Vary, Content-Encoding, Keep-Alive, Connection, Transfer-Encoding, Content-Type, Content-Language.
I don't see why PHP would add Content-Language: de, especially since all the software on this server is in English.
apachectl -ta2dismod negotiation, it tells me: "The following essential module will be disabled. This might result in unexpected behavior and should NOT be done unless you know exactly what you are doing!" Sounds dangerous, I'm gonna test it on a VM.