If you are unable to sign up affiliates due to an error message regarding the Referral ID, the issue is likely related to your active plugins.
Go to Plugins > Active Plugins in your merchant panel to review the currently activated plugins. One or more plugins may be conflicting with each other, causing the Referral ID error.
For example, you cannot use the Referral ID Length Constraint plugin—which enforces a specific length for referral IDs—together with the Username Referral IDs plugin, which generates referral IDs based on usernames. The likelihood of a username matching the required length is extremely low. To resolve this, you will need to deactivate one or more conflicting plugins. In this case, it is recommended to deactivate the length constraint plugin.
Test your affiliate signup process after deactivating conflicting plugins to ensure the error is resolved.
Do not activate plugins with overlapping functionality, as this can cause additional conflicts or errors.