Ubuntu 14.04 upgrade broke Apache2

Solution 1:

In moving up to Ubuntu 14.04, you are also passing to Apache 2.4 (from, presumably, 2.2). This is not a trivial change, you can find here the list of adjustments this requires. You will see there is some work to do. In particular, the page states (among other things):

These modules have been removed: mod_authn_default, mod_authz_default, mod_mem_cache.

That's why you get the error message above. You may try commenting out the offending line, 244 of apache.conf, and see whether your system can get by this way (but I doubt it).

Solution 2:

If you have your modules loading automatically from the mods-enabled directory then the offending line is likely in this section of your conf file:

# Include module configuration:
IncludeOptional mods-enabled/*.load
IncludeOptional mods-enabled/*.conf

In this case you will need to go to your mods-enabled directory (/etc/apache2/mods-enabled by default) and remove the symlink for the authz_default.load file.

This is because the symlink in mods-enabled will be pointing to a file in mods-available that no longer exists in Apache 2.4.