For many types of issue, the first step in troubleshooting is enabling WHMCS's error reporting system.
Enable hCaptcha or Invisible hCaptcha as your captcha type in WHMCS. hCaptcha offers checkbox-based and invisible captcha options to help you prevent bots from placing orders, creating accounts, or logging in to your Client Area or Admin Area. Before enabling hCaptcha or Invisible hCaptcha in WHMCS, you must configure it in your hCaptcha account.
Enable proforma invoicing, which ensures sequential invoice numbers for paid invoices. Some countries' accounting practices require this.
Enable reCAPTCHA v3 as your captcha type in WHMCS. reCAPTCHA v3 is an invisible captcha type that can help you prevent bots from placing orders, creating accounts, or logging in to your Client Area or Admin Area. Before enabling reCAPTCHA v3 in WHMCS, you must configure it in your Google® account.
Error pages display friendly, styled messages about error conditions. All of WHMCS's error pages are fully customizable for your needs.
WHMCS makes troubleshooting easier with built-in error handling.
Your system can use search-engine-friendly URLs for some public-facing pages.