Previously, we published a general guide on how to fix E: Sub-process /usr/bin/dpkg returned an error code message on SSH. Here is how to fix openssh-server E: Sub-process /usr/bin/dpkg returned an error. Do not close an active SSH session with this error. These errors are not uncommon on virtual servers, cloud servers for the virtual appliances. There can be a minor bug of the virtualization software or drop off some packets during the virtual server update process. The result becomes errors in postinst files. It is not dangerous on virtual servers than it delivers the feel. Virtual servers always have some way to “enter” by the admin. It is dangerous on dedicated servers.
Any web host will happily fix this error if you loss SSH connection and ask their help. But, we give importance to running some commands to test to fix own-self (which increases the experience of server administration).
Run these commands :
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1 2 3 | # ls -l /var/lib/dpkg/info | grep openssh # |
You’ll see list of files something like openssh-server.md5sums, openssh-server.postinst, openssh-server.postrm. Create a sub-directory under temporary with identifiable name :
1 2 3 | # mkdir -p /tmp/ssh-backup # |
Move all those files from /var/lib/dpkg/info to that temporary directory :
1 2 3 4 | # # cross-check the name openssh-server sudo mv /var/lib/dpkg/info/openssh-server.* /tmp/ssh-backup # |
Run :
1 2 3 4 5 6 7 | # sudo apt-get clean sudo apt-get update sudo apt-get upgrade # |
The package should not return the E: Sub-process /usr/bin/dpkg related error anymore. If still disturbs, your luck is bad. The problem is likely to be with /etc/apt/sources.list. You can try to restore sources.list to default, purge the unused software packages. You may try these :
1 2 3 4 | # sudo apt-get autoclean # |
You should take help of your web host to run :
1 2 3 | # sudo apt-get remove --purge openssh-server # |
I have not seen any good result by running the other common commands peoples usually suggest. As a rule, always carefully check all the log files for any attempt to breach the security of SSH. Virtual servers are vulnerable to various exploits which we can manage with physical components on the dedicated. But virtual servers offer a big advantage – web hosts provide free help even to the unmanaged servers around SSH and networking issues.
Always keep your servers updated, regularly reboot on need, notice the errors while updating & upgrading, check what software packages are not in use (apt list --installed list the packages).
