This was extremely helpful! I was trying to test a gateway that is still technically being used by an older 8.6.2 cluster, so I simply added a dial peer. However, all others were H.323, and this was one of the few SIP connected gateways on the 8.6.2 ...
I ran into this issue for ELM 11.0 with CER 11.0. I verified the version of CUCM was correct under the "CER Admin Utility". Once I have verified (but made no changes to) the CUCM version in CER Admin Utility, I rebooted the CER cluster and then re-ad...