MySQL/MariaDB error on the server with Plesk: Could not increase number of max_open_files to more than 16384

Applicable to:

Plesk for Linux

Symptoms

The following error can be seen when checking MySQL/MariaDB status via the

systemctl status mariadb

command:

[Warning] Could not increase number of max_open_files to more than 16384 (request: 32335).

MySQL/MariaDB performance is very slow.

Cause

Hard limit of the process exceeded the number set for open files limit (16384) in database server configuration files:

#Number of files limit
LimitNOFILE=16384

Resolution

Connect to the server via SSH
Find in which exact file the limit is set by executing the following commands:
```
# egrep -r LimitNOFILE /etc/systemd/system/m*
```
```
# egrep -r LimitNOFILE /lib/systemd/system/m*
```
Note: You are looking for a line that does not have a # in its beginning. That line contains the configuration that is active.
Once you find in which file the line
```
LimitNOFILE
```
is active, edit that file with your favorite command-line text editor and adjust the value:
```
LimitNOFILE=32335
```
Save the changes and close the file
Reload all daemons on the server:
```
# systemctl daemon-reload
```
Restart the mariadb or mysql service:
```
# systemctl restart mariadb
```

Article ID: 134
Created On: Sun, Aug 24, 2025 at 12:44 PM
Last Updated On: Sun, Aug 24, 2025 at 12:53 PM
Authored by: Saeed Nobakht [[email protected]]

Online URL: https://www.navel.ir/article/mysql-mariadb-error-on-the-server-with-plesk-could-not-increase-number-of-max_open_files-to-more-than-16384-134.html