2495694 - Enterprise Manager is offline due to error 'Invalid SSL message, peer seems to be talking plain!'

After perform the installation and configuration of an Introscope Enterprise Manager (EM) in the SAP Solution Manager system, the status of the EM is offline in step Configure CA Introscope. The following picture describes the issue:

In the defaultTrace files of the SAP Solution Manager JAVA stack/system, the following error is shown:

Error#com.sap.smd.introscope.em.rest.EmRestGateway#
#SV-SMG-DIA-APP#sap.com/tc~webadministrator~solmandiag####com.sap.smd.introscope.em.rest.EmRestGateway.test#Thread[ExRun:EMStatusRefresher_1,5,EMStatusRefresher:ExecTG]#Plain##
Error accessing to Enterprise Manager: enterprise.manager.host@6001
[EXCEPTION] com.sap.smd.introscope.em.IntroscopeException: java.io.IOException: Unable to open SSL connection to host "enterprise.manager.host:8081". Invalid SSL message, peer seems to be talking plain!.
at com.sap.smd.introscope.em.rest.IntroscopeHttpConnection.executeQuery(IntroscopeHttpConnection.java:157)
Caused by: java.io.IOException: Unable to open SSL connection to host "enterprise.manager.host:8081". Invalid SSL message, peer seems to be talking plain!.

• SAP Solution Manager 7.10 or 7.20
• SAP Solution Manager Diagnostics

SSL, HTTPS, WebView, Enterprise Manager, Instroscope , KBA , SV-SMG-DIA-WLY-EMS , Enterprise Manager Setup , XX-PART-WILY , Introscope by CA Technologies , Problem