Fix seafile server for folder names containing spaces

This is an apache bug.

Use a newer apache version:

Generic steps to install a newer version of a package with apt than provided in the stable stream:

In /etc/apt/apt.conf.d add the following file

99defaultrelease:

APT::Default-Release "stable";

In /etc/apt/sources.list.d – add urls for testing / unstable sources

stable.list:

deb     http://ftp.de.debian.org/debian/    stable main contrib non-free
deb-src http://ftp.de.debian.org/debian/    stable main contrib non-free

deb     http://security.debian.org/         stable/updates  main contrib non-free

testing.list:

deb     http://ftp.de.debian.org/debian/    testing main contrib non-free
deb-src http://ftp.de.debian.org/debian/    testing main contrib non-free

deb     http://security.debian.org/         testing/updates  main contrib non-free
run

apt-get update

and then install what you need with

apt-get -t testing install something

So for our purpose:

apt-get update
apt-get -t testing install apache2
service apache2 restart

Choose to keep all your default config files with no changes.

Credits:
Serverfault
https://wiki.debian.org/AptPreferences