503 Service Unavailable when Launching Enterprise Manager

I have recently faced an issue on a domain migration where, when accessing the Enterprise Manager console, the following error was shown: "Error 503-Service Unavailable".

By reading the Doc ID 1297193.1 on My Oracle Support I was able to figure out that the actual missing configuration was on the targets.xml file that holds the information of the Farm Domain the EM shall be targeting.

This targets.xml file is located under:
MW_HOME/user_projects/domains/<your_domain>/sysman/state


On my case, this file was empty so I had to add the necessary information for the EM application to connect to my target Farm:
<Targets>
<Target TYPE="oracle_ias_farm" NAME="Farm_soa_domain" DISPLAY_NAME="Farm_soa_domain">
<Property NAME="MachineName" VALUE="abc.com"/>
<Property NAME="Port" VALUE="7001"/>
<Property NAME="isLocal" VALUE="true"/>
<Property NAME="Protocol" VALUE="t3"/>
<Property NAME="serviceURL" VALUE="service:jmx:t3://abc.com:7001/jndi/weblogic.management.mbeanservers.domainruntime"/>
<Property NAME="WebLogicHome" VALUE="/u01/app/oracle/Middleware/wlserver_10.3"/>
<Property NAME="DomainHome" VALUE="/u01/app/oracle/Middleware/user_projects/domains/soa_domain"/>
</Target>
</Targets>

WEBLOGIC SERVER 11GR1 (10.3.6) UPGRADE INSTALLER

so many many patch update from oracle support, i'm tired locking for..but this is :
Patch 13529623: PLACEHOLDER BUG FOR WEBLOGIC SERVER 11GR1 (10.3.6) UPGRADE INSTALLER

ProductOracle WebLogic Server
PlatformGeneric Platform

Display thread stacks in weblogic

Display thread stacks

You can display the current stack for an active thread.
To display a thread stack:

1. In the left pane of the console, expand Environment > Servers.
2. On the Summary of Servers page, select the server instance for which you will request garbage collection.
3. Expand the Monitoring > Performance tab.
4. Click Dump Thread Stacks. 

BEA-280101 end BEA-000438

When i tuning WebLogic Integration 10.3 With 64-bit JDK on Sun Sparc.
I has done with support from site Oracle:

BEA-280101 warning while using Weblogic 10.3.3 on SPARC 64bit sun jvm

When you tuning weblogic and Startup it. In logs report errors BEA-280101

WebLogic Server overview

WebLogic Server contains Java 2 Platform, Enterprise Edition (J2EE) technologies. J2EE is the standard platform for developing multitier enterprise applications based on the Java programming language.