Servicing fails on step 6 while updating AOS

There are some hotfixes that patch modules and packages which are only available on the "onebox" sandbox (Tier 1) environments. If you happen to add these hotfixes to your VSTS Main Branch, you will most likely end up trying to install these modules and packages on your Tier 2 (ie UAT) environments, and this deployment will most likely fail. The reason is now the package has references to binaries which are not present on Tier 2.

One example is the module DemoDataSuite. From the deployment log you will find the following statement:

Running command: C:\DynamicsTools\nuget.exe install -OutputDirectory "G:\AosService\PackagesLocalDirectory\InstallationRecords" dynamicsax-demodatasuite -Source G:\DeployablePackages\GUID\AOSService\Packages

From the output, you would then find the following:

The running command stopped because the preference variable "ErrorActionPreference" or common parameter is set to Stop: Unable to resolve dependency 'dynamicsax-applicationfoundationformadaptor'.

It's true the DemoDataSuite depends on ApplicationFoundationFormAdaptor, and this Formadaptor Module is not on the Tier 2 environment. 

A simple solution is to simply change the default variables for the build defintion, and make sure the DemoDataSuite is excluded from package generation. 

Instructions on how to exclude named packages from the build can be found here:

https://docs.microsoft.com/en-us/dynamics365/unified-operations/dev-itpro/dev-tools/exclude-test-packages

If you suspect you've made custom modules and packages, and are worried they are causing your servicing to fail similarly, you may want to check the references yourself. Have a look at this post for more information on how to do that:

https://blogs.msdn.microsoft.com/axsupport/2017/04/10/resolving-a-missing-reference-during-package-deployment/