Just upgraded to 2.17 and and I cannot start apache2.
The error message is "Can't locate WWSafe.pm in @INC ..."
WWSafe.pm was in /opt/webwork/webwork2/lib before, but it is not there in 2.17. I copied the file and was able to start apache2.
check_modules.pl checks for Safe, but not for WWSafe.
I also have a WWSafe.pm file in /usr/local/share/perl/5.30.0, but that is not in @INC, another possible issue I had.