After an upgrade from Debian 9 to 10 we've got the following Errors in Apache2's error.log
Can't locate Apache/Ocsinventory/Plugins/Apache.pm in @INC (you may need to install the Apache::Ocsinventory::Plugins::Apache module) (@INC contains: /etc/perl /usr/local/lib/x86_64-linux-gnu/perl/5.28.1 /usr/local/share/perl/5.28.1 /usr/lib/x86_64-linux-gnu/perl5/5.28 /usr/share/perl5 /usr/lib/x86_64-linux-gnu/perl/5.28 /usr/share/perl/5.28 /usr/local/lib/site_perl /etc/apache2) at (eval 16) line 1.\n
Can't load Perl module Apache::Ocsinventory::Plugins::Apache for server 127.0.0.1:0, exiting...
Go to the mentioned folders and reneame from the version you have there to 5.28.1, Restart Apache.