The following error can occur when deploying an Oracle ADF to a newly installed weblogic 12c or 11g server :
Message icon - Error An error occurred during activation of changes, please see the log for details. Message icon - Error Error: Unresolved Webapp Library references for "WebAppModule(YOUR_APPLICATION:YOUR_APPLICATION.war)", defined in weblogic.xml [Extension-Name: adf.oracle.domain.webapp, exact-match: false], [Extension-Name: jstl, Specification-Version: 1.2, exact-match: false], [Extension-Name: jsf, Specification-Version: 1.2, exact-match: false]
Most of the times this error is simply occurring because your WebLogic server wasn’t installed with the Oracle ADF Runtime libraries.
To fix this, install the following on top of your fresh WebLogic server installation: https://oracle-base.com/articles/12c/weblogic-12c-adf-application-development-runtime-installation-on-oracle-linux
Feel free to comment if you encountered another cause for this issue.