Symptoms

Confluence does not start after running startup.sh.

Cause

Confluence's startup scripts won't override the value of CATALINA_HOME or CATALINA_BASE if they've already been set. Instead, they'll assume that it defines where tomcat should be running.

Resolution

Unset the variable, by either running unset CATALINA_HOME or unset CATALINA_BASE on Unix or Linux platforms, without the backticks, or removing CATALINA_HOME from the relevant user's profile scripts.