KBEC-00452 - Error installing CloudBees CD 10.0.x when Lang environment variable is different than en.US.UTF-8 – CloudBees Support

Symptom:

When upgrading to CloudBees CD 10.0 or 10.0.1 we are facing issues similar to:

Receiving error messages during the upgrade process similar to Error: Could not get the signature algorithm for the server's certificate
CloudBeew CD Web Page shows an error message similar to CloudBees Flow Server response was not recognizable.
In the CloudBees CD Installation Path/logs/setupScripts.log we can see errors similar to:

Running command: "/opt/electriccloud/electriccommander/bin/ecupgrade" 
Command ""/opt/electriccloud/electriccommander/bin/ecupgrade" " failed with exit code 0 and errors:
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
    LANGUAGE = (unset),
    LC_ALL = (unset),
    LANG = "en_US.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").

Issue:

When upgrading to CloudBees CD 10.0 or 10.0.1 Perl engine requires LANG environment variable equal to en.US.UTF-8.

Workaround:

Before executing the upgrade process, we need to change the LANG environment variable to en.US.UTF-8 executing:

export LANG=en.US.UTF-8

If we already started with an upgrade process and was stopped due to this issue we will also need to revert the current CloudBees CD folder to the previous status.

In the file CloudBees CD Installation Path/logs/installer.log look for the latest occurrence of the literal Renaming from '/opt/electriccloud/electriccommander' to, for example:

07/09/2020 14:25:46PM - Renaming from '/opt/electriccloud/electriccommander' to '/opt/electriccloud/electriccommander-9.2.0.139827'

and replace the current electriccommander folder with the backup done during the upgrade process, for example:

cd /opt/electriccloud
mv electriccommander ./electriccommander_backup
mv electriccommander-9.2.0.139827 ./electriccommander

Once done it and changed the LANG environment variable executing export LANG=en.US.UTF-8, you should be able to upgrade your system properly and after validating everything is working as expected we can remove the created electriccommander_backup folder.