I am doing a rolling upgrade of my production SQL 2016 Servers to SQL 2019. I have availability groups. My current structure is 3 DR servers (secondaries), 3 HQ (on prem) secondaries and 3 HQ primaries. I have updated 2 of the DR servers as per the upgrade instructions that I've found. The instructions say the 2019 DBs should be in synchronized mode, but my 2019 DBs are in Synchronized/In Recovery mode. I hope the "In Recovery" part is because the DRs are now SQL 2019 and the rest of the AG is SQL 2016 and when I failover from the primaries to the secondaries, there won't be any trouble. Is this the case?
I am using this reference during the upgrade.