Resolution
There should not be any problems if you update Apache because Plesk uses its own Apache for Control Panel and the Apache which serves users' websites is a part of the operating system distributive and can be updated freely. After Apache update you have to replace default Apache /usr/sbin/suexec with the Plesk one:
# cp $PRODUCT_ROOT_D/suexec/psa-suexec /usr/sbin/suexecmake sure that permissions are:
# ls -la /usr/sbin/suexec
-r-s--x--- 1 root apache 18720 Aug 24 13:29 /usr/sbin/suexecNote: group may differ depending on OS installed on the server, for example on SuSE it can be 'www'.
Note: in Plesk older than 7.5.4 psa-suexec is places in /usr/sbin/psa-suexec.
Keywords: how do i upgrade apache httpd