A BIG-IP Administrator upgrades the BIG-IP LTM to a newer software version. After the administrator reboots into the new volume, the configuration…

A BIG-IP system's license contains a "Service Check Date" which must be later than the "Service Required Date" of the software version being installed. Before performing a major software upgrade, the license must be reactivated to update this service check date. If an administrator upgrades to a new version for which the current license is not valid, the system will fail its license check upon rebooting into the new software volume. This license validation failure occurs before the configuration is loaded, thus preventing the system from loading its configuration files and entering an operational state.

A. The upgrade was performed on the standby unit.

This is the recommended best practice for upgrading a high-availability (HA) pair to minimize downtime and is not a cause of failure.

C. A minimum of at least two reboots is required.

A single, successful reboot into the newly installed software volume is the standard procedure. Multiple reboots are not a prerequisite for loading the configuration.

D. Connectivity to the DNS server failed to be established.

While DNS failure can cause issues with objects like FQDN pools, it does not typically cause a complete failure of the entire configuration loading process at boot time.

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1. F5 Networks Knowledge Base, K84205182: BIG-IP update and upgrade guide | Chapter 2: Preparing for an update or upgrade.

Section 2.1: Reactivate the license: "Before you perform a software installation, F5 recommends that you reactivate the BIG-IP system license. The BIG-IP license includes a service check date, and the BIG-IP software includes a service required date. The service check date in the license must be more recent than the service required date for the software version you want to install." This directly states license reactivation is a required preparatory step.

2. F5 Networks Knowledge Base, K7727: Reactivating your F5 product license.

Section: About the service check date: "If the license service check date is earlier than the software service required date, the BIG-IP system fails to load the configuration and reports a license error." This confirms that an outdated license service date will cause a configuration load failure.

3. F5 Networks Knowledge Base, K7752: Troubleshooting BIG-IP license activation.

Section: Error Messages: This article lists common error messages related to licensing. An error such as "LICENSESTATUSEXPIREDMAINTENANCE" can occur during an upgrade attempt if the license is not valid for the new version, leading to a failure state where the configuration cannot be loaded.