Plesk Onyx for Linux kb: technical ABT: Group A
- Plesk Onyx for Linux
- Plesk for Linux
Websites periodically are not available with one of the errors below:
CONFIG_TEXT: 502 Bad gateway
CONFIG_TEXT: 504 Gateway Time-out (nginx)
The following error can be found in Apache Web Server log files (
/var/log/apache2/error.logon Debian and Ubuntu,
/var/log/httpd/error.logon RHEL, CentOS and CloudLinux):
CONFIG_TEXT: [mpm_event:error] [pid 22565:tid 140163371042688] AH00485: scoreboard is full, not at MaxRequestWorkers.Increase ServerLimit.
MPM mode is set to Event in Tools & Settings > Apache Web Server.
Apache bug with ID #53555.
As a workaround, the following steps can be performed to Switch to MPM Prefork.
Open Tools & Settings > Apache Web Server.
Change MPM mode to Prefork or Worker, if it is available.
This suddenly happens to our server today. The bug stated it was fixed but as what happened today, this does not
As I can see, the bug should be fixed in Apache 2.4.7. The latest official available version is 2.4.38 (http://httpd.apache.org/download.cgi), so the bug might still appear.
Server version: Apache/2.4.6 (CentOS)
Mine is not updated, how do I update and will it be safe?
CentOS 7 is currently supporting Apache 2.4.6. Plesk does not support custom Apache versions, only default one that is provided by OS repository is supported.
Okay so we are starting to experience this issue as well. I think it's time that Plesk would update Apache completely as this bug was already fixed in newer Apache versions.
Apache 2.4.6 was released in 2013 (!) in the meantime the latest version is Apache 2.4.46 (august 2020).
I understand Plesk cannot update Apache every time to a newer version, however still running 2.4.6 is a bit absurd.
Furthermore there are quite a few CVE fixes in the newer versions along with several new performance tweaks / options.
So I would urge Plesk to update Apache to something more modern. This should be possible for at least CentOS 7.x (I understand that for CentOS 6.x the urge is lower, as it will become EOL by the end of the year).
Sidenote; I noticed Plesk with CentOS 8.x is running on Apache/2.4.37. So it should be possible for CentOS 7.x as well imho.
I also checked our DirectAdmin servers and even the older ones like with CentOS 6.x are running modern versions of Apache (e.g. Apache/2.4.41). So I don't understand why Plesk is lacking in this department. Especially considering Plesk is a premium control panel interface and should be modern in all ways.
And it shouldn't be needed for customers, like us (with many servers), to tweak various settings in order to have Plesk functioning normally.
Just my 2 cents.
Hello Michel vd Lingen,
I would like to notice that Plesk uses packages that are available in the official repositories. In that case, the latest available version for CentOS 7 is the following:
# yum info httpd | grep "Version\|Release"
Version : 2.4.6
Release : 93.el7.centos
However, it does not mean that the package is in the same state as in 2013. There is Backporting Security Fixes exist:
As you can check, some fixes are applied to the package from time to time. For example, the latest update was on Mar 31, 2020:
# rpm -q --changelog httpd | grep 93.el7.centos
* Tue Mar 31 2020 CentOS Sources <email@example.com> - 2.4.6-93.el7.centos
Hello Michel vd Lingen
In addition to my colleague's comment. To preserve your feedback I've created a user suggestion. RnD looks through suggestions and in case of popularity, this change is likely to be done.
> And it shouldn't be needed for customers, like us (with many servers), to tweak various settings in order to have Plesk functioning normally.
I agree with you that it would be great and could make the life of a hoster much easier. However, the difficulty here is that each hosting server is unique and optimal configuration varies from server to server. From time to time RnD adjusts web server and PHP default setting to comply more with modern standards.
Thank you for sharing your thoughts.
About the "Configure logrotate to restart Apache instead of reloading" solution.
My /etc/logrotate.d/apache2 on Ubuntu 18 and Plesk 18.0.37 has this line:
and I don't see httpdmng having a "restart" option
Indeed, such an option is not available to httpdmng on more recent updates. I updated the article accordingly. Thank you for bringing this to our attention
I followed instructions and changed mpm mode to Prefork (the only available other option) but when I enable this option http2 is no longer available?
AH10034: The mpm module (prefork.c) is not supported by mod_http2. The mpm determines how things are processed in your server. HTTP/2 has more demands in this regard and the currently selected mpm will just not do. This is an advisory warning. Your server will continue to work, but the HTTP/2 protocol will be inactive.
Any help is appreciated
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