Unable to connect to Plesk 18.0.80 from WHMCS: This element is not expected

Symptoms

• Plesk Obsidian is updated to version 18.0.80 or later.
• WHMCS is connected to the Plesk server.

• When performing an action from WHMCS (for example, syncing accounts, or suspending/unsuspending a service), the following error appears:

  CONFIG_TEXT: Module Command Error Error code: 1014. Error message: Parser error: Request is invalid. Error in line 2: Element 'domain': This element is not expected. Expected is one of ( request-settings, server, customer, webspace, subdomain, dns, db_server, mail, certificate, site-alias ).

Cause

The WHMCS Plesk module sends an invalid XML API request. Starting with Plesk 18.0.80, schema validation rejects this request. This is a bug WHMCS-27532 that will be fixed in future updates.

Resolution

As a workaround, until an updated WHMCS module is released:

1. Back up the panel.ini file:

   # cp /usr/local/psa/admin/conf/panel.ini /usr/local/psa/admin/conf/panel.ini.bak

2. Edit the panel.ini file — see How to edit Plesk panel.ini — and add the following lines to it:

   CONFIG_TEXT: [api]
   deprecationError = off

3. Remove the deprecationError = off line from panel.ini once the WHMCS Plesk module has been updated — panel.ini settings are kept intact through Plesk updates.