Symptoms
-
Apache 2.4.10 crashes with the following error in its error log:
(35)Resource deadlock avoided: AH00144: couldn't grab the accept mutex
[fcgid:warn] [pid 14206] mod_fcgid: process 23611 graceful kill fail, sending SIGKILL
[fcgid:warn] [pid 14206] mod_fcgid: process 22505 graceful kill fail, sending SIGKILL
[core:alert] [pid 23133] AH00050: Child 22989 returned a Fatal error... Apache is exiting! -
Apache
mpm_prefork
mode is used:# apache2ctl -V | grep MPM
Server MPM: prefork
Cause
Unclear.
Resolution
-
Connect to the Plesk server via SSH.
-
Open the file
/etc/apache2/apache2.conf
in a text editor. In this example, we are using the vi editor:# vi /etc/apache2/apache2.conf
-
Find the following line:
Mutex file:${APACHE_LOCK_DIR} default
and change it to:
Mutex posixsem
-
Save the changes and close the file.
-
Restart the Apache service:
# service apache2 restart
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If Apache continues to crash, switch Apache MPM mode to Event in Plesk at Tools & Settings > Apache Web Server.