In the document you sent, the causes are documented, they are the bugs.
Bug 21383809 : APPS LOCAL LOGIN IS GIVING ERROR 404 AND OACORE DEPLOYMENT IN FAILED STATE
Bug 21384732 : APPS LOCAL LOGIN IS GIVING ERROR 404 AND OACORE DEPLOYMENT IN FAILED STATE
So, if you issue is the same, then your causes are the same.
If your issue is different, then it must be investigated.
Even a wrong apps password may make your oacore/oafm managed servers to remain in the admin state.
http://erman-arslan-s-oracle-forum.2340467.n4.nabble.com/Weblogic-managed-servers-td3819.html