If you are getting errors while upgrading your tier-1 environment, trust me you are not alone, many of us facing this error say,
Error 1:
Stop script for service model: AOSService on machine
If you remember this is the same issue we had with the earlier version, and to fix this you have to update the VC++ runtime. You can download this from the below link and run it on our tier-1 environment (s).
Error 2:
GlobalUpdate script for service model: RetailServer on machine:(VM Name)
Let's understand why, (Or let's see what the fix is :) )
Whenever you Apply any update from LCS, it will create a package on VM local disk normally at the below location
ServiceVolume\DeployablePackages and you have to select the most recent folder (in case you already tried a few times with this error).
Navigate to RetailServer\Scripts and find the file name 'DropAllRetialChannelDbObjects'.
Here is the entire path in case you need it (ServiceVolume\DeployablePackages\RetailServer\Scripts\DropAllRetialChannelDbObjects), run this SQL query on AXDB on VM and try again to apply the update.
Tip: This SQL script sometimes takes hours and hours to finish, you can try to stop this execution and select one query at a time from the script.