1. Read the installation and upgrade notes included with the release you will install. Confirm WHMCS, PHP, database and extension compatibility for that release.
2. Back up the WHMCS database, current module files and the persistent secrets directory. Keep the encryption master key and connector-signing keys with the matching recovery set.
3. Record the installed version, enabled services, cron configuration and any local customisations. Keep custom branding or translation changes documented so they can be reapplied through supported settings.
4. Review pending domain orders, funding recovery and DNS changes. Allow normal work to finish where practical. Investigate uncertain paid operations before opening another path that could resubmit them.
5. Apply the upgrade first to a protected staging environment when your licence and deployment arrangements permit it. Ensure staging cannot send real registrar orders or production notifications.

Upload the new package into the WHMCS root while preserving its directory layout. Follow the release's migration procedure and open the addon to complete required upgrade steps. Reuse the existing protected keys. Regenerating encryption keys can make previously encrypted credentials unreadable, and changing signing material can affect connector trust.

Do not use the addon's Delete module data when deactivating option during an upgrade. Deactivation with destructive cleanup enabled is an uninstall action. Taking a backup first does not turn it into an appropriate upgrade step.

Confirm the displayed version, then inspect Readiness & diagnostics and Jobs & runtime. Test a provider connection, a controlled DNS change, client-area navigation and a reseller read request. Check that cron continues to advance queued jobs and that the installation uses the intended web and command-line PHP runtimes.

For connectors, check whether the release calls for new builds or updates. An addon upgrade and a downloaded reseller connector update are related but separate deployments. Keep existing credentials protected during either process.

Capture the error, release version and relevant job identifiers before changing state. Restore files, database and secrets as a consistent set under an agreed maintenance procedure. A file-only rollback may be unsafe after database migrations. Never retry a paid registrar request merely because the interface was unavailable; reconcile its provider and operation status first.

• Install Domain Nexus in WHMCS and initialise its secure storage
• Keep Domain Nexus jobs, scheduled DNS changes and reconciliation running
• Configure DNS backups and restore a reviewed record snapshot
• Build and publish branded billing-platform connectors in Connector Studio

• WHMCS system requirements