Error: Could not find or load main class weblogic.Server

 Error: Could not find or load main class weblogic.Server while starting Demantra Managed server 

Solution : 

Weblogic Server Fails to Start With Node Manager - "Error: Could Not Find Or Load Main Class Weblogic.Server" (Doc ID 2311678.1)

StartScriptEnabled=true is needed to allow nodemanager to load the required classpath and java_options and other to come up successfully.

To get WebLogic server started properly with NodeManager, add the below parameter <WL_HOME>/common/nodemanager/nodemanager.properties file :

"StartScriptEnabled=true"

reference:
Node Manager Administrator's Guide for Oracle WebLogic Server
4 Configuring Java Node Manager
https://docs.oracle.com/cd/E28271_01/web.1111/e13740/java_nodemgr.htm