Hi,
we have a single projection (per-context) which emits events to a bounded context stream based on a string in their metadata.
This projection was written at least 1,5 years ago, wasn’t changed since then and never noticed any problems associated with it until now.
Yesterday evening, these errors occured inside our Event Store production instance:
» 24 Sep 2015 17:55:10.212 [PID:26097:013 2015.09.24 15:54:55.084 ERROR ProcessingStrategySe] The per-context projection failed to process an event.
» 24 Sep 2015 17:55:10.212 Handler: EventStore.Projections.Core.Services.v8.DefaultV8ProjectionStateHandler
» 24 Sep 2015 17:55:10.212 Event Position: C:990603520/P:990603520
» 24 Sep 2015 17:55:10.212
» 24 Sep 2015 17:55:10.212 Message:
» 24 Sep 2015 17:55:10.212
» 24 Sep 2015 17:55:10.212 Source array type cannot be assigned to destination array type.
» 24 Sep 2015 17:55:10.212 System.ArrayTypeMismatchException: Source array type cannot be assigned to destination array type.
» 24 Sep 2015 17:55:10.212 at (wrapper stelemref) object:virt_stelemref_sealed_class (intptr,object)
» 24 Sep 2015 17:55:10.234 at EventStore.Projections.Core.Services.v8.V8ProjectionStateHandler.ProcessEvent (System.String partition, EventStore.Projections.Core.Services.Processing.CheckpointTag eventPosition, System.String category, EventStore.Projections.Core.Services.Processing.ResolvedEvent data, System.String& newState, System.String& newSharedState, EventStore.Projections.Core.Services.Processing.EmittedEventEnvelope[]& emittedEvents) [0x00000] in :0
» 24 Sep 2015 17:55:10.234 at EventStore.Projections.Core.Services.Processing.EventProcessingProjectionProcessingPhase.ProcessEventByHandler (System.String partition, EventStore.Projections.Core.Messages.CommittedEventReceived message, System.String& newState, System.String& newSharedState, System.String& projectionResult, EventStore.Projections.Core.Services.Processing.EmittedEventEnvelope[]& emittedEvents) [0x00000] in :0
» 24 Sep 2015 17:55:10.234 at EventStore.Projections.Core.Services.Processing.EventProcessingProjectionProcessingPhase.SafeProcessEventByHandler (System.String partition, EventStore.Projections.Core.Messages.CommittedEventReceived message, System.String& newState, System.String& newSharedState, System.String& projectionResult, EventStore.Projections.Core.Services.Processing.EmittedEventEnvelope[]& emittedEvents) [0x00000] in :0
``
» 24 Sep 2015 17:55:11.426 [PID:26097:010 2015.09.24 15:54:56.549 ERROR ProjectionManager ] The ‘per-context’ projection faulted due to 'The per-context projection failed to process an event.
» 24 Sep 2015 17:55:11.426 Handler: EventStore.Projections.Core.Services.v8.DefaultV8ProjectionStateHandler
» 24 Sep 2015 17:55:11.426 Event Position: C:990603520/P:990603520
» 24 Sep 2015 17:55:11.426
» 24 Sep 2015 17:55:11.426 Message:
» 24 Sep 2015 17:55:11.427
» 24 Sep 2015 17:55:11.427 Source array type cannot be assigned to destination array type.’
``
As all our catch up subscriptions depend on this projection working correctly, we would gladly help in diagnosing this further. I did not (yet) restart our Event Store instance (though I have to in the next few hours to bring our services back online) so any tests that require this current fault state should be done soon. As this is the first time this happened to us in ~1,5 years, I’d guess reproducing it is pretty hard.
I know projections are not yet defined as stable, but this is a pretty trivial one and if I understand the roadmap correctly, there are only 1-2 months left until they are meant to be stable.
Thanks & Regards,
Nicolas