After upgrading my master 3.8 BM server this morning to 3.9 one of my two
S2S connections came back and the other did not. On the IKE Screen, I see
the error "Discard: NO IKE SA is available and exchange type is neither
Main Mode nor Aggressive Mode 5 from <ip of slave that didn't come back>
Cookie xxxxxx.

key management type for both s2s connections was IKE before the upgrade.
Now, the server that isn't connecting says "Unknown type 0"

How can I fix this?