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MECM – Cannot get Multicast Key

Problem:

Multicast does not start and using CMTRACE to check the logs at X:\Windows\Temp\SMSTS reveals that your multicast session could not get a multicast key

.Open Regedit and check: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SMS\MCS

Typically there are approximately 30 items listed here, but if Multicast is broken, there may be closer to 5-10, and both SerializedMCSKey and SignedSerializedMCSKey will likely be empty.

Solution:
  1. Uncheck “Allow this package to transfered via multicast” at packages and your install image properties.
  2. Remove the “SerializedMCSKey” and “SignedSerializedMCSKey” keys in registry at HKLM\Software\SMS\MCS.
  3. Uncheck “Enable multicast” at the properties of the Distribution Point.
  4. Wait for 30 to 60 minutes until multicast is fully removed from the Distribution Point. Check this in the SCCM console under the site roles status view and check the log files on the distribution point.
  5. Check “Enable multicast” at the properties of the Distribution Point.
  6. Check if the “SerializedMCSKey” and “SignedSerializedMCSKey” keys in registry at HKLM\Software\SMS\MCS are populated again. This could take a couple of minutes or a couple of hours. If SerializedMCSKey appears but SignedSerializedMCSKey doesn’t appear after several hours, try rebooting your server. The signed key should then also fill in.
  7. Check “Allow this package to transfered via multicast” at packages and your install image properties.
  8. Wait again for 15 to 30 minutes until the packages are multicast enabled. A background process runs to do this. Microsoft recommended to wait around 15 to 30 minutes.