I am facing the same problem with Fisheye 2.2.1 version (while upgrading from 2.0.6 to this version).

The /fisheye context is not getting initialized due to this and thus not available through http. But on the back end side, I see that the fisheye is indexing all the repositories and is visible in the debug logs.

I tried downloading the artifacts again (as mentioned could be due to corrupt download), but that didn't resolve the problem.