'apache2 -t' shows error on a Plesk for Debian-based OS: DefaultRuntimeDir must be a valid directory, absolute or relative to ServerRoot

Symptoms

On Debian-based OSes, Apache configuration test command apache2 -t returns the error:

# apache2 -t
[Mon Feb 10 00:18:28.636153 2025] [core:warn] [pid 22859:tid 22859] AH00111: Config variable ${APACHE_RUN_DIR} is not defined
apache2: Syntax error on line 80 of /etc/apache2/apache2.conf: DefaultRuntimeDir must be a valid directory, absolute or relative to ServerRoot

Cause

Apache bug on Debian-based OSes.

Resolution

As a workaround, use apache2ctl -t or apachectl -t to check Apache configuration.