From your tc Server instance configuration you are used
Listener classname="com.springsource.tcserver.properties.SystemProperties"
as described here.
Then on catalina.properties you also added more than one property source:
org.apache.tomcat.util.digester.PROPERTY_SOURCE = com.springsource.tcserver.security.PropertyDecoder,org.apache.tomcat.util.digester.EnvironmentPropertySource
as described on tomcat docs you can specify multiple classes separated by comma but this throws an error:
source[com.springsource.tcserver.security.PropertyDecoder,org.apache.tomcat.util.digester.EnvironmentPropertySource].
java.lang.ClassNotFoundException: com.springsource.tcserver.security.PropertyDecoder,org.apache.tomcat.util.digester.EnvironmentPropertySource
You checked and made sure classes specified in PROPERTY_SOURCE is existing. If you only put one class instead of 2 classes the error/exception above is not thrown.
tc Runtime Version: 9.0.87.B.RELEASE and earlier versions
tc Runtime Version: 10.1.20.A.RELEASE and earlier versions
This is a known bug with com.springsource.tcserver.properties.SystemProperties and are fix on the following tc Server versions: