Sharepoint - Upgrade required even after product configuration wizard was successfull

This sometimes happens because the timer job CreateProductVersionJob didn't run as expected and you can try to restart the SharePoint timer service in services.msc.

If that doesn't do the trick, you run the PowerShell script Get-SPProduct -local. Even if it is a Get-script it does update the ConfigDB. It also forces the CreateProductVersionJob to start an update of the server registry.

You may need to run PSCONFIG again after this script, but this solves the mismatch problem in 95% of the cases I encounter this error. If not the account you're using doesn't have sufficient permission on the ConfigDB or isn't local admin on the server while upgrading.

Reference: SharePoint Patching and Get-SPProduct -local

If this don't help, you have to use more arguments in your psconfig script. I use this one which always work.

PSConfig.exe -cmd upgrade -inplace b2b -wait -force -cmd applicationcontent -install -cmd installfeatures -cmd secureresources 

this is known issue in sharepoint 2013 and 2016. You can safely ignore it. But if you want to get rid of this message then please run this run command.

psconfig -cmd -upgrade inplace b2b -force 

Hopefuly, Microsoft will fix this in upcoming CU.