This are the modules of PHP or webservers which are known to cause problems with ownCloud:
with entries like:
in your vhosts file.
Apache with mod_php and enabled mod_spdy (SPDY) module
Running Apache with mod_spdy enabled could lead to various issues when using mod_php:
The following documentation shows how to switch to mod_fcgid:
mod_auth_apple on Mac OS X server
There is a module mod_auth_apple available on Mac OS X servers which is doing the Basic Auth like on an apache server. Disable this module.
eAccelerator PHP module
How to disable it: (Thanks to RandolfCarter for this link)
Instead of the settings like described in the linked article it is possible to disable the whole extension. Where this extension is loaded depends on the installation / system / used distro. This article describes how the extension is loaded:
On debian this .so file is loaded in /etc/php5/conf.d/ for example.
PHP OPcache configuration
When setting the PHP directive opcache.save-comments to 0 in your php.ini you need to set it to 1 again to avoid problems with the CSRF check / protection of ownCloud.
Webserver WebDAV modules
OwnCloud brings it’s own WebDAV PHP implementation (SabreDAV). Enabling the WebDAV module of your webserver can cause many problems with OwnCloud. This are the WebDAV modules of the most common webservers:
Webserver security modules
Some webserver security modules are also known to be problematic when running on your webserver:
libapache2-mod-php5filter installed instead of libapache2-mod-php5 (php5filter don’t pass all needed methods to PHP)
mod_pagespeed when having upgrade problems
Problematic server configurations
Some tutorials recommending adding the following lines for “security” or “performance” reasons to your /etc/apache2/conf.d/security on Ubuntu:
Header unset ETag FileETag None
Those changes will break the ownCloud sync client and will cause an “The server did not provide an Etag” or “No E-Tag received from Server” error in the client. (Thanks to blitt001 for reporting this)
You need to remove those lines to be able to work with the sync client.