Just a minor problem I found when upgrading Jira Data Center (in my case, from 8.16.0 to 8.20.12).
The installer will process [Jira Install Dir]/bin/setenv.sh, but if you have line-continuation in the file, e.g.:
JVM_SUPPORT_RECOMMENDED_ARGS=" \ -Dsomething=something \ -Danotherthing=something \ "
After upgrade it will become:
And setenv.sh will fail, not setting the environment variables. And you will likely end up with errors complaining that -Xmx and -Xms are not set large enough.
The solution is to combine those lines back into one for the upgrade, or put your settings back after the upgrade.