I've tested replicating this on a brand new EC2 VM running precise 12.04.1, steps were as follows sudo -i echo "deb http://repo.percona.com/apt precise main" >> /etc/apt/sources.list echo "deb http://repos.zend.com/zend-server/deb server non-free" >> /etc/apt/sources.list apt-get update apt-get install zend-server-php-5.3 # Works fine apt-get install percona-server-server root@ip-10-178-67-248:~# apt-get install percona-server-server Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: percona-server-server : Depends: percona-server-server-5.5 but it is not going to be installed E: Unable to correct problems, you have held broken packages. You can try and force it but then it tries to uninstall zend apt-get install percona-server-server percona-server-server-5.5 percona-server-client-5.5 percona-server-common-5.5 Reading package lists... Done Building dependency tree Reading state information... Done The following packages were automatically installed and are no longer required: php-5.3-soap-zend-server php-5.3-curl-zend-server php-5.3-xsl-zend-server libapache2-mod-php-5.3-zend-server lighttpd-zend-server php-5.3-posix-zend-server php-5.3-debugger-zend-server libicu36 libpng3 sqlite php-5.3-cm-utils-pe-zend-server php-5.3-monitor-ui-zend-server php-5.3-bin-zend-server php-5.3-sockets-zend-server php-5.3-ftp-zend-server php-5.3-ctype-zend-server zend-base php-5.3-page-cache-zend-server php-5.3-pdo-oci-zend-server libcap2 php-5.3-gd-zend-server php-5.3-zem-zend-server php-5.3-sqlite-zend-server cli-tools-zend-server libapr1 php-5.3-sc-zend-server zend-server-doc php-5.3-zip-zend-server php-5.3-zend-extensions php-5.3-ldap-zend-server php-5.3-optimizer-plus-zend-server libsqlite0 deployment-daemon-zend-server php-5.3-monitor-zend-server php-5.3-fcgi-zend-server php-5.3-json-zend-server php-5.3-calendar-zend-server libaprutil1-ldap apache2-mpm-prefork php-5.3-pdo-pgsql-zend-server php-5.3-mcrypt-zend-server apache2-utils php-5.3-phar-zend-server php-5.3-imap-zend-server libmcrypt4 php-5.3-oci8-zend-server apache2.2-common libframework1-zend-server php-5.3-zendutils-zend-server libaprutil1-dbd-sqlite3 zend-server-framework php-5.3-zds-zend-server apache2.2-bin jobqueue-zend-server deployment-extension-zend-server ssl-cert php-5.3-bcmath-zend-server php-5.3-tokenizer-zend-server php-5.3-fileinfo-zend-server jq-daemon-zend-server php-5.3-mbstring-zend-server php-5.3-tidy-zend-server php-5.3-gettext-zend-server liboci-us-locales-zend zend-server-framework2 libssl0.9.8 php-5.3-exif-zend-server libpq5 php-5.3-jq-zend-server php-5.3-dev-zend-server php-5.3-code-tracing-zend-server php-5.3-session-clustering-zend-server php-5.3-bz2-zend-server php-5.3-pgsql-zend-server php-5.3-intl-zend-server libaprutil1 php-5.3-data-cache-zend-server sc-daemon-zend-server Use 'apt-get autoremove' to remove them. The following extra packages will be installed: libdbi-perl libmysqlclient18 libnet-daemon-perl libplrpc-perl Suggested packages: tinyca The following packages will be REMOVED: libmysqlclient15off mysql-common php-5.3-common-extensions-zend-server php-5.3-gui-zend-server php-5.3-mysql-zend-server php-5.3-mysqli-zend-server php-5.3-pdo-mysql-zend-server zend-server-php-5.3 The following NEW packages will be installed: libdbi-perl libmysqlclient18 libnet-daemon-perl libplrpc-perl percona-server-client-5.5 percona-server-common-5.5 percona-server-server percona-server-server-5.5 0 upgraded, 8 newly installed, 8 to remove and 37 not upgraded. Need to get 0 B/68.2 MB of archives. After this operation, 208 MB of additional disk space will be used. Do you want to continue [Y/n]? ^C