Nessus Offline Activation License Already In Use [top] Jun 2026

Locate the Nessus activation code that is giving you trouble. Look for a "Reset" or "Unlink" button next to the license.

Reinstalling Nessus or rebuilding a server without first explicitly resetting or deregistering the old instance.

/opt/nessus/sbin/nessus-fetch --challenge

You can fix this error by resetting your license in the Tenable Community Portal. Why This Error Happens nessus offline activation license already in use

💡 : Always keep a backup of your nessuscli fetch --challenge output. If your hardware profile changes (like swapping a NIC), your challenge code changes, which will trigger a license mismatch. If you’re still stuck, I can help you:

You must release the license from the old hardware signature before activating it on the new one. Navigate to the and log in. Click on My Products from the main dashboard.

On an internet-connected computer, navigate to Tenable's official offline activation page at https://plugins.nessus.org/v2/offline.php . Locate the Nessus activation code that is giving you trouble

Once the code is reset, you can proceed with the standard offline registration process: Generate a New Challenge Code : On your offline machine, run the command nessuscli fetch --challenge to get a fresh, unique code. Generate License File : On a machine with internet access, visit the Nessus Offline Registration page

Performing an offline activation for Tenable Nessus is a standard procedure for securing air-gapped environments, isolated lab networks, and high-security zones. However, the process can be disrupted by the frustrating error:

Stop the Nessus service:

"C:\Program Files\Tenable\Nessus\nessuscli.exe" fetch --register-offline nessus.license Use code with caution. Install the plugin package:

You must manually reset the activation code through the Tenable Support Portal to make it available for a new challenge code. Log in to the Tenable Community/Support Portal .

What (Windows or Linux) is your offline Nessus scanner running on? If you’re still stuck, I can help you:

Look for an option labeled Manage Product or Reset Activation Code.

If the original system is no longer accessible—for example, if the hard drive failed or the operating system was completely reinstalled—you must reset the activation code through Tenable's official portal.