Is there a particular way to update from debian 7 to debian 8 on a machine on Google Compute Engine?

While I can connect to the machine with gcloud ssh command, after I did the update I'm unable to connect from the Console using SSH on browser; I get a "Could not connect, retrying (1/3)..." error. For the update process I follow the documentation on Debian official website.

The error on console log is: instance-1 sshd[18651]: Connection closed by XX.XXX.XX.XX [preauth]

Nothing more and I have already tried to restart the machine.

So, the questions are: - Is there specific documentation for Google Compute Engine for update debian 7 to debian 8? - Have anyone make the update, get my error and solve the issue about ssh from browser?



1 Answer 1


First, it is not recommended to upgrade the OS in place. Instead you should deploy the application on an image of the next version.

Also, this question is now one year old. Debian 7 Wheezy is not supported anymore.

I was able to upgrade Debian 7 to Debian 8 Jessie in Compute Engine. I just replaced "wheezy" with "jessie" in /etc/apt/source.list and /etc/apt/source.list.d/* and then ran a "apt-get dist-upgrade".

See the Debian Jessie upgrading documentation for all about upgrading from 7 to 8. https://www.debian.org/releases/jessie/amd64/release-notes/ch-upgrading.en.html.

I tried with both:

  • The latest standard Debian 7 image "debian-7-wheezy-v20160531". It's still available but deprecated.

    It appears to work. If you try on one of your projects be careful: the image is 1.5 years old and hasn't received security updates.

  • A new image built from https://github.com/andsens/bootstrap-vz/blob/master/manifests/official/gce/deprecated/wheezy-backports.yml.

    It works mostly, what I noticed is that /etc/hosts file is missing the name of the machine, and the hostname defaults to "localhost". I am not sure why but that still does not break ssh.

Regarding the sshd error:

instance-1 sshd[18651]: Connection closed by XX.XXX.XX.XX [preauth]

It means that the ssh client closed the connection during the SSH preauthentication phase.

It often means that the the sshd daemon can't read the user's ~/.ssh/* files. The error messages above this line could bring more information, you can also try adding "-vv" to the ssh command.

If you still have the issue, I suggest you follow the "Troubleshooting SSH errors " part of the troubleshooting guide https://cloud.google.com/compute/docs/troubleshooting#ssherrors.

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