(Reading database ... 104216 files and directories currently installed.)
Removing apache2-mpm-prefork ...
invoke-rc.d: unknown initscript, /etc/init.d/apache2 not found.
dpkg: error processing apache2-mpm-prefork (--purge):
 subprocess pre-removal script returned error exit status 100
Errors were encountered while processing:
 apache2-mpm-prefork
E: Sub-process /usr/bin/dpkg returned an error code (1)
A package failed to install.  Trying to recover: