D365 (DevVM): BestPractise broken after updating to PU28 - dynamics-365

Question

I have a Dynamics365 DevVM and updated it from 10PU26 to 10PU28 so that i develop on the same platform version as the systems i am developing for. After applying 10pu28 i started my VisualStudio, changed something and tried to save and compile but noticed that BP is broken and so i can't develop further. Visual Studio logs the following but i am not sure what i can do to fix this.
Build started 07/25/2019 06:27.
Build step: Metadata validation started.
Exception occured while performing operation Validate Metadata. Exception details: Path: []:System.ArgumentNullException: Value cannot be null.
Parameter name: source
at System.Linq.Enumerable.Contains[TSource](IEnumerable`1 source, TSource value, IEqualityComparer`1 comparer)
at Microsoft.Dynamics.Framework.Tools.ILGeneratorAgent.CompilationService.ValidateMetadata(String module, String metadataPath, String compilerMetadataPath, IEnumerable`1 referencedAssembliesFolders, IEnumerable`1 elements)
Build step: Metadata validation completed (10 ms).
Build step: X++ compilation, label generation and resource deployment started.
Build step: X++ compilation, label generation and resource deployment completed (670 ms).
Build step: Best practice check started.
Exception occured while performing operation Best practice checks. Exception details: BP Rule: [Exception occured while performing operation Best practice checks. Exception details]:System.ArgumentNullException: Value cannot be null.
Parameter name: referencedAssembliesFolders
at Microsoft.Dynamics.Framework.Tools.ILGeneratorAgent.MetadataProviderExtensions.AddReferenceProvider(IMetadataProvider provider, IEnumerable`1 referencedAssembliesFolders, IDiagnosticSink diagnostics, String modelModule, MetadataProviderFactory factory)
at Microsoft.Dynamics.Framework.Tools.ILGeneratorAgent.CompilationService.RunBestPracticeChecks(String module, String metadataPath, String compilerMetadataPath, IEnumerable`1 referencedAssembliesFolders, IEnumerable`1 elements, String modelName, Boolean isNormalizedCollectionNeeded)
Build step: Best practice check completed (9 ms).
Build completed (716 ms).
I attempted to disable running BP when building as a temporary workaround but that didn't work either. When BP is disabled i still can't compile. Here are the logs:
Build started 07/25/2019 06:40.
Build step: Metadata validation started.
Exception occured while performing operation Validate Metadata. Exception details: Path: []:System.ArgumentNullException: Value cannot be null.
Parameter name: source
at System.Linq.Enumerable.Contains[TSource](IEnumerable`1 source, TSource value, IEqualityComparer`1 comparer)
at Microsoft.Dynamics.Framework.Tools.ILGeneratorAgent.CompilationService.ValidateMetadata(String module, String metadataPath, String compilerMetadataPath, IEnumerable`1 referencedAssembliesFolders, IEnumerable`1 elements)
Build step: Metadata validation completed (8 ms).
Build step: X++ compilation, label generation and resource deployment started.
Build step: X++ compilation, label generation and resource deployment completed (381 ms).
Build completed (409 ms).

Answer 1

This issue can be caused if the update did not successfully update all components. This in turn can be caused if the default topology file is used for the update. The documentation by Microsoft is a bit confusing on this part of the update process (see issue 1137). Make sure to change the topology file according to section Collect topology configuration data in the documentation.
I also recommend to take a look at the d365fo.tools, which include the powershell function Invoke-D365SDPInstall that does a lot of the work in the updgrade process for you (including the update of the topology file).