How to reproduce the issue:

1. Access the Crucible admin section by only inserting the master / root password (by accessing http://HOST:PORT/admin/login-default.do)
2. Go to Admin >> Project Settings >> Projects >> <choose the project> >> Click on "Application Links" link
3. The message is displayed:

   No entity exists with key ${helper.project.key} of type com.atlassian.applinks.api.application.fecru.FishEyeCrucibleProjectEntityType 
   

This message, however, does not say what is really going on.
To solve the problem, the user must be logged in with an admin user (by accessing http://HOST:PORT/login?origUrl=/).

I believe that this error could provide more details, or that maybe this screen should enforce there's an admin user logged in.

Please let me know if you need any additional information.

Thanks a lot,
Felipe Kraemer
Atlassian Support