If you still have access to the old Nessus installation (before you wiped the OS or uninstalled), you must deactivate it from the command line before moving to a new instance.
On Linux:
/opt/nessus/sbin/nessuscli fetch --register-offline <your_activation_code>
(Note: If the machine is truly offline, this may fail to contact the server. In this case, simply uninstalling Nessus usually clears local data, but the backend reset (Method 1) is still required.)
Once you have resolved the "already in use full" error, take these preventive measures to avoid recurrence.
The error indicates that the same license key has already been registered against a different Nessus scanner instance.
Offline activation ties the license to the scanner’s Challenge Code (a unique identifier derived from the system’s hardware and hostname). When you request an offline license file from Tenable, that file is bound to the specific Challenge Code of the machine at that time.
If you:
→ Tenable’s activation server rejects the new activation with “License already in use.”
Since you are performing an offline activation, standard internet-based deactivation methods will not work. Choose the solution below that fits your situation.
If you frequently manage multiple offline Nessus scanners, consider an enterprise solution that supports license pooling and offline activation without the "full" limit. Nessus Professional is not designed for fleet management.
The system fingerprint changed. You need Solution 2 (Tenable support reset) or Solution 5 (force overwrite + new trial license if applicable).
If you still have access to the old Nessus installation (before you wiped the OS or uninstalled), you must deactivate it from the command line before moving to a new instance.
On Linux:
/opt/nessus/sbin/nessuscli fetch --register-offline <your_activation_code>
(Note: If the machine is truly offline, this may fail to contact the server. In this case, simply uninstalling Nessus usually clears local data, but the backend reset (Method 1) is still required.) nessus offline activation license already in use full
Once you have resolved the "already in use full" error, take these preventive measures to avoid recurrence.
The error indicates that the same license key has already been registered against a different Nessus scanner instance. If you still have access to the old
Offline activation ties the license to the scanner’s Challenge Code (a unique identifier derived from the system’s hardware and hostname). When you request an offline license file from Tenable, that file is bound to the specific Challenge Code of the machine at that time.
If you:
→ Tenable’s activation server rejects the new activation with “License already in use.”
Since you are performing an offline activation, standard internet-based deactivation methods will not work. Choose the solution below that fits your situation. (Note: If the machine is truly offline, this
If you frequently manage multiple offline Nessus scanners, consider an enterprise solution that supports license pooling and offline activation without the "full" limit. Nessus Professional is not designed for fleet management.
The system fingerprint changed. You need Solution 2 (Tenable support reset) or Solution 5 (force overwrite + new trial license if applicable).