Unable to reconfigure apache server.conf: RemoteIP: Error parsing IP RemoteIPInternalProxy

Symptoms

• Plesk Obsidian versions 18.0.56 (all updates) and 18.0.57 running on a Linux-based operating system
• Reconfiguration of the Apache /etc/httpd/conf/plesk.conf.d/server.conf file via Tools & Settings > Webserver Configurations Troubleshooter fails with the following error:
  

  PLESK_ERROR: Syntax error on line 4215 of /etc/httpd/conf/plesk.conf.d/server.conf: RemoteIP: Error parsing IP RemoteIPInternalProxy (Name or service not known error) for RemoteIPInternalProxy.

• The server is configured to use more than 100 dedicated IP addresses

Cause

This issues is caused by a known Plesk bug with ID PPPM-14195. The bug prevents the server.conf file of Apache from being reconfigured when a great number of IP addresses are added to the server. A fix will be applied in future updates of Plesk.

Resolution

Until the bug is resolved permanently, you may apply the following workaround:

1. Log into your server via SSH

2. Use your favorite command-line text editor to update the default Plesk template file /usr/local/psa/admin/conf/templates/default/server/remoteip.php with the following content:

CONFIG_TEXT: <IfModule <?php echo $OPT['mod'] ?>>
<?php
$ipAddresses = $VAR->server->webserver->listenLocalhost ?
[$VAR->server->ipAddresses->loopbackIpAddress] :
$VAR->server->ipAddresses->all;
$vhostIpCapacity = $VAR->server->webserver->apache->vhostIpCapacity;
?>
<?php for ($ipAddress = reset($ipAddresses); $ipAddress; $ipAddress = next($ipAddresses)): ?>
RemoteIPInternalProxy <?php echo $ipAddress->address ?><?php for ($n = 1; $n < $vhostIpCapacity && $ipAddress = next($ipAddresses); $n++) { echo " {$ipAddress->address}"; } ?>
<?php echo "\n"; ?>
<?php endfor; ?> RemoteIPHeader X-Forwarded-For
</IfModule>

3. Save the changes

4. Reconfigure the Apache server.conf file via Tools & Settings > Webserver Configurations Troubleshooter once again