This article was created in response to a support issue logged with K2. The content may include typographical errors and may be revised at any time without notice. This article is not considered official documentation for K2 software and is provided "as is" with no warranties.


The K2 Blackpearl service fails to start and returns the following error: 

Error Starting Host Server: System.TypeInitializationException: The type initializer for 'SourceCode.Data.Dac' threw an exception. ---> System.MissingMethodException: Method not found: 'System.String System.String.Format(System.IFormatProvider, System.String, System.Object)'.
at SourceCode.Diagnostics.Logging.LoggingFactory.CreateLoggerInstance(RuntimeTypeHandle typeHandle)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at SourceCode.Diagnostics.Logging.LoggingFactory.CreateLogger[T]()
at SourceCode.Data.Dac..cctor()


It was determined that Microsoft .NET Framework 4.6.1 was not installed via the release key, as per:

Troubleshooting Steps

As .NET Framework 4.6.1 is required for K2 Blackpearl version 4.7, please install it on the server to resolve the issue.