That could be due to several reasons:
1- The license might not have the year version of the product you are trying to activate, for instance, 2019, or the expiration date within the file needs to be updated, or the product you are trying to activate is not listed on the license file.....
So, please go to this link upload your license file and check if the product you are trying to activate is listed there and check also if the expiration date is up to date.
So, please go to this link upload your license file and check if the product you are trying to activate is listed there and check also if the expiration date is up to date.
2- Wrong information on the license file (license was encrypted on wrong MAC (Ethernet address) or hostname).
Please upload the file to the link I've sent on the topic above, upload the file and check either if the MAC or HOSTNAME are correct.
3- The default TCP port, 2080, used by Autodesk Network Licensing daemon, adskflex, is blocked.
Please go to your Firewall settings, add the ports 2080, 27000-27009 as TCP and set them to Allow the connection
More info on this link.
More info about this error can be found here.