I have installed koha on Ubuntu in VirtualBox. Following are my Koha Server Information. Server information Koha version: 18.11.03.000 OS version ('uname -a'): Linux StaticStudy 4.15.0-46-generic #49-Ubuntu SMP Wed Feb 6 09:33:07 UTC 2019 x86_64 Perl interpreter: /usr/bin/perl Perl version: 5.026001 Perl @INC: /usr/share/koha/lib /etc/perl /usr/local/lib/x86_64-linux-gnu/perl/5.26.1 /usr/local/share/perl/5.26.1 /usr/lib/x86_64-linux-gnu/perl5/5.26 /usr/share/perl5 /usr/lib/x86_64-linux-gnu/perl/5.26 /usr/share/perl/5.26 /usr/local/lib/site_perl /usr/lib/x86_64-linux-gnu/perl-base MySQL version: mysql Ver 14.14 Distrib 5.7.25, for Linux (x86_64) using EditLine wrapper Apache version: Server version: Apache/2.4.29 (Ubuntu) Memcached: Servers: 127.0.0.1:11211 | Namespace: koha_library | Status: running. | Config read from: koha-conf.xml Zebra version: Zebra 2.0.59 (C) 1994-2014, Index Data Zebra is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. SHA1 ID: c00bfddbf0f3608340d61298acc61dafb167f9b2 Using ICU Date and time: 04/09/2019 09:12 Time zone: Used: Asia/Kolkata | Config: Undefined | Environment (TZ): Undefined I try to start and eneble 'Plack' through following commands sudo koha-plack --enable library sudo koha-plack --start library sudo service apache2 restart Sometimes these commands work just fine and I get a significant boost in speed. But after I turn off the virtual box and try to access it later, koha stops working (nothing appears on 127.0.0.1:8080 & 8081) untill I disable Plack through the following commands sudo koha-plack --stop library sudo koha-plack --disable library sudo service apache2 restart. And the speed also reduces significantly. Restarting Plack doesn't work. Please guide me to solve this problem.