Installation Guide – Troubleshooting cPanel & WHM Installation

1. Introduction

This guide explains additional troubleshooting steps to follow if you installed cPanel & WHM but still encounter issues. These solutions address common problems such as SSL warnings, license errors, package failures, and hostname or resolver issues.

Important: If you complete all troubleshooting steps and still experience issues, contact cPanel Support. You can grant access through the Grant cPanel Support Access interface.

2. Security Certificate Warnings

Problem

You see the message: There is a problem with this website's security certificate.

Explanation

During installation, cPanel & WHM installs a self‑signed SSL certificate for your hostname. If your server does not use a valid FQDN or cannot obtain a free certificate from Let’s Encrypt, the system will continue using the self‑signed certificate. Modern browsers do not trust self‑signed certificates, which triggers a security warning.

Solution

• Ensure your server uses a valid FQDN. Update it in WHM:
  WHM » Home » Networking Setup » Change Hostname
• If supported by your hosting provider, the system will automatically install a free Let’s Encrypt hostname certificate.
• If automatic issuance is not allowed, purchase and install a certificate via:
  WHM » Home » SSL/TLS » Purchase and Install an SSL Certificate

3. License Errors

Problem

You see errors such as License File Expired during or after installation.

Explanation

• Your license may be expired or misconfigured.
• Your server may not connect to WebPros International license servers.
• Your hostname may be invalid.
• Your server’s date or time may be incorrect.

Solution

Follow the steps in the How to Fix License File Errors documentation to resolve this issue.

4. Perl Installation Errors

Problem

You see the error:
Fatal! Perl must be installed before proceeding!

Explanation

Perl must be installed before the cPanel & WHM installer can run. If Perl is missing, the installer attempts to install it automatically:

• On RHEL‑based systems: yum -y install perl
• On Ubuntu systems: apt -y install perl perl-base

If these commands fail, the installer displays the error. You should not manually modify the system Perl installation.

Solution

• On AlmaLinux, CentOS, or CloudLinux, ensure yum works, then run:
  

  yum install perl

• On Ubuntu, ensure apt works, then run:
  

  apt -y install perl-base

5. High CPU Load on Hyper-V

Problem

Your server shows high CPU usage while Hyper‑V Dynamic Memory is enabled.

Explanation

This issue is caused by a known Hyper‑V sleep interruptibility bug.

Solution

Visit the LKML website for the patch and additional details.

6. Package Installation Failures

Problem

One or more RPM or .deb packages fail during installation.

Explanation

Package failures may occur due to repository issues, dependency conflicts, or system misconfiguration.

Solution

• For RPM issues, refer to the RPM Installation Failures documentation.
• There is currently no official documentation for .deb installation failures on Ubuntu.

7. Resolver Errors

Problem

You see the warning:
The system DNS resolvers went missing when cPanel adjusted the hostname.

Explanation

This occurs when your hostname does not resolve properly, causing the system to assign an automatic hostname and attempt to repair missing DNS resolvers.

On systems running AlmaLinux 9, Rocky Linux 9, or CloudLinux 9, the installer:

• Writes the following to /etc/NetworkManager/conf.d/99-cpanel.conf to prevent overwriting /etc/resolv.conf:

  [main]
  dns = none

• Reloads the NetworkManager service.

The installer then restores the previous /etc/resolv.conf file.

Solution

• Update resolvers in:
  WHM » Home » Networking Setup » Resolver Configuration
• Update your hostname in:
  WHM » Home » Networking Setup » Change Hostname

8. Hostname Issues on Cloud‑Hosted Servers

Problem

Your cloud server does not retain its hostname.

Explanation

The hosting provider’s dhclient script may override the hostname set by cPanel & WHM.

Solution

Follow the steps in the Cloud-Hosted Hostname Solution documentation.

9. Installation Issues with ESET

Problem

Some servers experience installation failures when using ESET File Security.

Explanation

This issue occurred due to conflicts with cPanel & WHM version 88 and earlier.

Solution

ESET is a third‑party product, and cPanel does not provide support for it.

10. Experimental Installation on Unsupported Operating Systems

Overview

This method allows installation of cPanel & WHM on unsupported operating systems by disabling most OS detection. This feature was introduced in version 102.

Important: Installing on unsupported systems is experimental and may cause unexpected behavior. cPanel does not provide support for these environments.

Installation Command

Use the following command, replacing operatingsystem with a supported OS identifier:

sh latest --experimental-os=operatingsystem

Example:

sh latest --experimental-os=almalinux-8.4

Conclusion

By following these troubleshooting steps, you can resolve most issues that occur during or after installing cPanel & WHM. Proper hostname configuration, valid licensing, functional package managers, and correct resolver settings are essential for a stable and successful installation.