I am running Perfect Server on CentOS 6. Everything was working fine until I decided to do upgrades last night. I first upgraded packages (yum upgrade) and then upgraded ISPConfig. Now I am having nothing but problems and I wish I had left well enough alone. Code: Linux myhost.com 2.6.32-042stab116.2 #1 SMP Fri Jun 24 15:33:57 MSK 2016 x86_64 x86_64 x86_64 GNU/Linux To begin, I am getting 500 errors every other page load for sites on my server. I cannot seem to track down a reason. The only thing I see is that php-cgi is now causing OOM errors, but I don't know how to diagnose that any further. I'm seeing dozens of these over and over in /var/log/messages. Code: Mar 3 18:15:08 myhost kernel: [14805396.443762] Out of memory in UB 474: OOM killed process 11586 (php-cgi) score 0 vm:203876kB, rss:84512kB, swap:0kB Mar 3 18:15:10 myhost kernel: [14805398.387054] Out of memory in UB 474: OOM killed process 12109 (php-cgi) score 0 vm:208044kB, rss:89948kB, swap:0kB Mar 3 18:15:12 myhost kernel: [14805400.516331] Out of memory in UB 474: OOM killed process 12060 (php-cgi) score 0 vm:202756kB, rss:85224kB, swap:0kB Mar 3 18:15:15 myhost kernel: [14805403.339489] Out of memory in UB 474: OOM killed process 11973 (php-cgi) score 0 vm:205844kB, rss:88396kB, swap:0kB Mar 3 18:15:16 myhost kernel: [14805404.700555] Out of memory in UB 474: OOM killed process 12422 (php-cgi) score 0 vm:208920kB, rss:92184kB, swap:0kB Mar 3 18:15:19 myhost kernel: [14805407.487566] Out of memory in UB 474: OOM killed process 11494 (php-cgi) score 0 vm:199392kB, rss:82116kB, swap:0kB Mar 3 18:15:21 myhost kernel: [14805409.106790] Out of memory in UB 474: OOM killed process 12561 (php-cgi) score 0 vm:206024kB, rss:88268kB, swap:0kB The system PHP was updated as was Apache. However, some of the affected sites are running on alternate PHP versions, not the system version. Also, mail delivery has stopped. All messages are being deferred as shown in /var/log/maillog Code: Mar 3 18:21:00 myhost postfix/smtp: 0C8563E00E9A: to=<[email protected][email protected][email protected][email protected][email protected] I'm lost as to where to go from here. I've double checked main.cf and all looks good. All services are running. I am running CSF, but I am not seeing any corresponding firewall rules being triggered.