Your physical server’s network card died. You replaced the NIC or moved the hard drive to entirely new hardware. The Challenge Code (based on the old NIC) is no longer valid, but Tenable’s servers still show that your license key is tied to that dead hardware’s Challenge Code.
Once the license is reset on the Tenable side, you need to get a fresh Challenge Code from your offline scanner to ensure you aren't using cached, stale data.
The site will now generate a nessus.license file since the code is no longer marked as "in use". 3. Apply the License Offline
Key points to understand about Nessus licensing: nessus offline activation license already in use
If the old machine is still accessible, you can try to "unlink" it locally by running nessuscli fetch --deactivate while it has an internet connection, though this is rarely possible in air-gapped environments.
Since you are performing an offline activation, Tenable’s servers believe the code is active on another machine. Tenable Community Portal Navigate to My Products and select your Nessus subscription. Find the specific Activation Code you are trying to use. Manage/Reset
Run the following command to register the offline license file you transferred: Your physical server’s network card died
Installing Nessus in a virtual machine (like VMware or VirtualBox) can be tricky. Some free licenses are tied to a specific virtual hardware signature. Cloning a VM or migrating it to a new host can sometimes trigger the "already in use" error because the license perceives it as a new, separate device.
file to your offline scanner and register it using the command line: nessuscli fetch --register-offline nessus.license Alternatively, upload it via the Nessus web interface under Settings > Registration > Offline Additional Troubleshooting Resources Official Docs Community Fixes Plugin Updates Tenable Documentation Tenable Offline Installation Guide
: Provide the new Challenge Code and the Activation Code you just reset. Once the license is reset on the Tenable
You must be the owner of the code (registered to your account) for the reset option to appear. Also, be aware that there is a time limitation on how frequently you can reset an activation code – often a 10‑day waiting period between resets.
A previous Nessus instance was deleted or shut down permanently without transferring or unregistering the license. Step-by-Step Solutions to Resolve the Error