Deregister Licence after crash

After installing an UiPath Studio, we have registered this installtion with an licence-key, we have received from UiPath, like: 123456789098765432
After a crash from the client, we cannot user the utility: Regutil to create a “deactivation certificate”.

How we can release this blocked license without a deactivation certificate?
Thanks for your help. Best regards
Urs Buck

Version: UiPath 18.1.1
MSI: UiPathPlatform_2018.1.msi