When trying to upload a new SEP License for the Threat Attack Analysis feature on the Symantec Endpoint Detection and Response appliance, you see the error "Failed to upload license". You will also be unable to remove the old/expired SEP license.
This can happen when an on premise sandbox server is used instead of Cynic.
This issue is currently under investigation with Symantec and will be resolved in a future software release.
As a workaround, the following steps can be taken: