EnvironmentError: The environment options "TRAC_ENV" or "TRAC_ENV_PARENT_DIR"
or the mod_python options "TracEnv" or "TracEnvParentDir" are missing.

Yuck. What’s more, if you’re using SuExec (like I am) then your Apache directives are ignored.

Solution: Edit your trac.fcgi and prepend the following code.

# hack for SuExec
import os;
os.environ['TRAC_ENV_PARENT_DIR'] = ‘/var/lib/trac’