I am a big fan of Oracle Enterprise Manager Cloud Control 12c. I am also a fan of using the EMCLI to setup and modify my Oracle OEM 12c targets. Recently I spent a lot of time going around in circles trying to figure out adding a target and getting the error: ORA-20247: EMD_URL is invalid: Cannot provide null emd url.
Well I would almost categorize this in as a typo. It turns out that the -host=”rac02a” was incorrect. The proper name of the host in OEM was fully qualified. Once I replaced the -host parameter with -host=”rac02a.perftuning.com” it all worked properly. The error message is a bit cryptic. So, if you see this error, check the host string.