Symptoms

Unable to send client event notifications. The error below was found on the logs:
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"Error","Extensibility","63004","ComposeFail","SourceCode.Server.Extensibility.CompositionServices","63004 Failed to compose object: System.ComponentModel.Composition.ChangeRejectedException: The composition remains unchanged. The changes were rejected because of the following error(s): The composition produced multiple composition errors, with 2 root causes. The root causes are provided below. Review the CompositionException.Errors property for more detailed information.

1) No valid exports were found that match the constraint '((exportDefinition.ContractName == 'SourceCode.MessageBus.MessageParameterFormatter') AndAlso (exportDefinition.Metadata.ContainsKey('ExportTypeIdentity') AndAlso 'SourceCode.MessageBus.MessageParameterFormatter'.Equals(exportDefinition.Metadata.get_Item('ExportTypeIdentity'))))', invalid exports may have been rejected.

Resulting in: Cannot set import 'SourceCode.MessageBus.Server.MessageBusRuntime._formatter (ContractName='SourceCode.MessageBus.MessageParameterFormatter')' on part 'SourceCode.MessageBus.Server.MessageBusRuntime'.

Element: SourceCode.MessageBus.Server.MessageBusRuntime._formatter (ContractName='SourceCode.MessageBus.MessageParameterFormatter') --> SourceCode.MessageBus.Server.MessageBusRuntime

2) No valid exports were found that match the constraint '((exportDefinition.ContractName == 'SourceCode.MessageBus.ILoggingService') AndAlso (exportDefinition.Metadata.ContainsKey('ExportTypeIdentity') AndAlso 'SourceCode.MessageBus.ILoggingService'.Equals(exportDefinition.Metadata.get_Item('ExportTypeIdentity'))))', invalid exports may have been rejected.
Resulting in: Cannot set import 'SourceCode.MessageBus.Server.MessageBusRuntime._logging (ContractName='SourceCode.MessageBus.ILoggingService')' on part 'SourceCode.MessageBus.Server.MessageBusRuntime'.
Element: SourceCode.MessageBus.Server.MessageBusRuntime._logging (ContractName='SourceCode.MessageBus.ILoggingService') --> SourceCode.MessageBus.Server.MessageBusRuntime
===

 

Diagnoses

It was found that the segment below was missing from the K2HostServer.exe.config file:








 

Resolution

Adding the missing part then restarting the service helped resolved the issue