Upgrade Azure Devops Server 2019 to Azure Devops Server 2020

I am trying to Upgrade Azure Devops Server 2019 to Azure Devops Server 2020 looking for some best practice Thanks

[1040:2C34][2021-04-02T03:04:37]i000: MUX:  Online feed url authoring not found  [1040:2C34][2021-04-02T03:04:37]i000: MUX:  Warning Block: ProcessBlock : Please close the Azure DevOps Server Administration Console before continuing.  [1040:2C34][2021-04-02T03:04:37]i000: MUX:  Online feed url authoring not found  

https://stackoverflow.com/questions/66902651/upgrade-azure-devops-server-2019-to-azure-devops-server-2020 April 01, 2021 at 06:15PM