This problem can happen in beta versions of MistikaVR 8.8.7  (it will be fixed in the final release)

If MistikaVR refuse to open with a "license error: 6000" message with no evident reason (that is, if you have an internet connection and a valid subscription, the license server running, and you have already activated the activation code but you still see the error 6000)  then do this:

- Reboot the system a first time and try again, if not yet

- The license file could be corrupted or uncompleted.   It can happen in rare cases, if it was installed manually or if the licensing process crashed in someway.  You can refresh the license file by deleting it and doing a reboot (in this way, the license server will connect automatically and it will get a new license file online).  The license file is named sgoLicenseV5.dat, and it is in the directory %PROGRAMDATA%/sgo in the case of Windows,  or in the /var/flexlm folder  in the case of Mac and Linux.  Delete it and reboot the system

- If none of the above solved the problem then we recommend to deactivate the activation code (etiher with the SGOActivation tool or in your online account) , also remove the license file as explained  (sgoLicenseV5.dat). Then activate the activation code again and reboot. 

Please note that this article only covers a very specific problems of 8.8.7 beta. For more details about other license issues please read the generic document about the licensing system