Nessus Offline Activation License Already In Use Page

Encountering the error during a Nessus offline activation can halt your vulnerability management workflow. This guide explains why this error happens and provides actionable steps to resolve it quickly. Why This Error Occurs

The "License already in use" error during Nessus offline activation can seem daunting, but it can usually be resolved through careful verification of license keys, releasing licenses from previous installations, and communicating with Tenable Support when needed. By understanding the causes and taking preventative measures, Nessus users can minimize downtime and ensure their vulnerability scanning capabilities remain operational.

/opt/nessus/sbin/nessuscli fetch --register-offline nessus.license

Download the nessus.license file and the plugin archive ( all-2.0.tar.gz ). nessus offline activation license already in use

: This frees the license so it can be paired with your new offline challenge code. E-SPIN Group 2. Deactivate via Command Line (If you have access)

After running the reset command, restart the Nessus service. Your activation code is now free to be used for the new offline activation. How to Complete the Offline Activation Correctly

Download the nessus.license file and the provided custom plugin URL link. Step 3: Apply the License to the Offline Host Encountering the error during a Nessus offline activation

Modifying virtual machine hardware triggers a new challenge code.

Rolling back a virtual machine to a state before Nessus was fully configured, or cloning a Nessus VM, clones the hardware UUID but breaks the cryptographic trust link with the license.

: Find your Nessus Professional license and click Manage Product . E-SPIN Group 2

The error is a classic symptom of hardware identity mismatch in air-gapped environments. It is not a bug—it is a security feature preventing license theft. However, it is a frustrating feature when legitimate hardware fails or gets cloned.

Once the code is reset, return to your offline machine to generate a new challenge string. : Run /opt/nessus/sbin/nessuscli fetch --challenge .