I installed the newest Stardog 7.8.0 and i was not able to connect from to localhost using Studio
As a test, i connected to CLI without any issues using the same default admin:admin username and password
c:\stardog-7.8.0\bin>stardog-admin query list --run-as admin -P
Password for user admin:
0 queries running.
I tested the same steps on Server 7.7.3 and it was ok