With this error message a SSH command to Gerrit is rejected if the SSH authentication is not successful.
The SSH protocol uses Public-key Cryptography for authentication. This means for a successful SSH authentication you need your private SSH key and the corresponding public SSH key must be known to Gerrit.
If you are facing this problem, do the following:
Verify that you are using the correct username for the SSH command and that it is typed correctly (case sensitive). You can look up your username in the Gerrit WebUI under Settings → Profile.
Verify that you have uploaded your public SSH key for your Gerrit account. To do this go in the Gerrit WebUI to Settings → SSH Public Keys and check that your public SSH key is there. If your public SSH key is not there you have to upload it.
Verify that you are using the correct private SSH key. To find out which private SSH key is used test the SSH authentication as described below. From the trace you should see which private SSH key is used.
Test SSH authentication
To test the SSH authentication you can run the following SSH command. This command will print out a detailed trace which is helpful to analyze problems with the SSH authentication:
$ ssh -vv -p 29418 firstname.lastname@example.org
If the SSH authentication is successful you should find the following lines in the output:
... debug1: Authentication succeeded (publickey). ... **** Welcome to Gerrit Code Review **** Hi John Doe, you have successfully connected over SSH. Unfortunately, interactive shells are disabled. To clone a hosted Git repository, use: git clone ssh://email@example.com:29418/REPOSITORY_NAME.git ...
Part of Gerrit Error Messages