Upgrading Your 3CX PBX

Author: Kevin Fortune
Version: Applies to 3CX v18 and v20

This article summarizes the official upgrade process for 3CX PBX systems based on guidance from 3CX. Always ensure you have reliable backups and a maintenance plan before upgrading.

Before You Begin

• Ensure you have a valid and recent backup of your PBX.
• Verify your operating system meets the requirements of the newer version.
• Confirm you have root/administrator access to the server.
• Review your firewall, DNS, and SSL certificate configurations.
• If upgrading across multiple major versions, a migration path may apply.

1. Back Up Your PBX

Before upgrading, take a full backup:

• Sign in to the 3CX Management Console.
• Navigate to Settings → Backup.
• Create a backup including: System configuration, Extensions, Recordings (optional), License key.
• Download and store the backup in a safe location.

2. Update the OS and Packages

Ensure your system is up to date:

sudo apt update && sudo apt upgrade -y

Reboot if required by the package manager.

3. Upgrade the PBX

Linux (Debian / Ubuntu)

Run the 3CX upgrade script:

sudo apt install 3cxpbx

If upgrading from very old versions, the installer may require a new OS installation followed by restoring your backup.

Windows Systems

Download the latest 3CX installer from 3cx.com and run it directly over your existing install. The installer will:

• Detect your current version
• Upgrade services and configuration
• Prompt for reboot if necessary

4. Restore if Needed

If something goes wrong or you choose a migration reinstall:

1. Install the new version cleanly
2. Choose Restore Backup during setup
3. Upload the backup file you created earlier

5. Post-Upgrade Tasks

• Verify SIP trunks register successfully
• Test inbound & outbound calls
• Confirm extension mobility apps reconnect
• Review firewall checker and 3CX security warnings
• Validate custom SSL certificates
• Reapply any custom templates if required

Notes & Warnings

• Upgrading from unsupported versions (e.g., v15, v16) may require a full migration reinstall.
• The 3CX Linux version is strongly tied to specific Debian releases; upgrading OS versions without reinstall is not supported.
• Always verify your license key is active before upgrading.

Need Assistance?

If you require live upgrade support, Deerfield’s 3CX-certified technicians can assist via a paid support session.

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