Troubleshoot Your WHMCS Module

WHMCS (Web Host Manager Complete Solution) is a third-party billing and automation platform widely used by hosting resellers. Two different OpenSRS modules can appear inside WHMCS — one built by WHMCS, one built by OpenSRS — and most support issues come from confusion between them or from misconfigured API connectivity. This guide helps you identify which module you're using and resolve the most common errors.

About the two WHMCS modules

WHMCS ships with its own built-in OpenSRS registrar module. OpenSRS also publishes a separate, more feature-rich module called Opensrspro (the Domains Pro module). The two modules use different code paths, log differently, and are configured separately, so the first troubleshooting step is always to confirm which one is handling a given domain.

Before you begin

• You have administrator access to your WHMCS instance.
• You have access to your OpenSRS reseller account at manage.opensrs.com to verify your API key and IP whitelist.
• You can run commands from the WHMCS server's command line (or have someone who can) to test outbound connectivity to the OpenSRS API.
• If you have not yet installed the Opensrspro module, see Install and Use the OpenSRS Domains Pro Module for WHMCS.

Step 1: Determine which WHMCS module you are using

In your WHMCS admin area, go to Setup > Products/Services > Domain Registrars.

If you only see "OpenSRS"

You are using the WHMCS-developed module. For setup and troubleshooting of that module, see the WHMCS documentation at docs.whmcs.com/OpenSRS.

If you see both "OpenSRS" and "Opensrspro"

You have successfully installed the OpenSRS-developed module. Activate Opensrspro (if it is not already active) and configure it with your reseller account credentials.

To see which domains are managed by Opensrspro, go to Clients > Domain Registrations. Domains using the OpenSRS module will have the Registrar column set to Opensrspro.

Step 2: Resolve a "Registrar Error" / authentication error

You see a message like:

Authentication Error. For support regarding [domain], please contact your reseller, via the following:

This error indicates one of two problems:

• You are using the WHMCS-built OpenSRS module and the registrant data has not yet been imported into the WHMCS database, or the registrant username/password stored in WHMCS is incorrect. See the WHMCS docs on importing existing domains.
• You are trying to manage a domain that does not exist in the reseller account configured in the module.

Step 3: Resolve "oSRS Error" connection problems

You see one of these messages:

oSRS Error - No Content-Length header returned. Please make sure IP is whitelisted in RWI. Check the osrs_key and osrs_username in the config file as well.
oSRS Error - Read buffer is empty. Please make sure IP is whitelisted in RWI. Check the osrs_key and osrs_username in the config file as well.

These errors mean your server cannot reach the OpenSRS API. Check the following:

• The Opensrspro module is configured with the correct reseller name and API key.
• Your server's outbound IP address is whitelisted under Account Settings > API Settings > IP Access Rules in your OpenSRS reseller account.
• Your server and firewall allow outbound TCP traffic on ports 55000 and 55443 to rr-n1-tor.opensrs.net.

Verify the connection by running:

telnet rr-n1-tor.opensrs.net 55000

A successful response looks like 0.9 XCP VERSION CHECK XML:0.1 OpenSRS SERVER ready.

Step 4: Resolve a blank screen after a module action

If you perform a module action and the page returns blank, a PHP dependency is usually missing. To surface the underlying error:

• Enable display_errors in your server's PHP configuration.
• In WHMCS, go to Setup > General Settings > Other and turn on Error Reporting.

Resubmit the same action. The PHP error message will now appear with the detail you need to fix the dependency.

Step 5: Investigate changes that are not being reflected

When module actions appear to succeed but nothing changes, check the WHMCS Module Logs:

• Go to Utilities > Logs > Module Logs.
• If logging is disabled (the default), enable it and resubmit your change.
• Locate the row for your request and review the Response column for the cause.

Each log entry shows the timestamp, the module, the action, and the JSON request and response.

Next steps

• Confirm your install is complete — If Opensrspro is missing or only partially configured, see Install and Use the OpenSRS Domains Pro Module for WHMCS.
• Re-run the telnet test after changes — Any time you change firewall rules or IP whitelisting, re-run telnet rr-n1-tor.opensrs.net 55000 to confirm connectivity before retrying module actions.
• Collect logs before contacting support — Have the timestamp, request payload, and response from Module Logs ready when you open a support ticket. It significantly speeds up diagnosis.

Questions? Contact OpenSRS Support.