Error: Internal server error

If you get the following error when pushing to your local development Gerrit instance

To ssh://admin@localhost:29418/testproject
 ! [remote rejected] HEAD -> refs/for/master (internal server error)
error: failed to push some refs to 'ssh://admin@localhost:29418/testproject'

then you probably need to flush the Gerrit caches. This can be done with the flush-caches command.

ssh -p 29418 admin@localhost gerrit flush-caches