Intermittent ArgumentException "Mix spatial references are not supported" on startup

markcheyne

Occasionally when my Silverlight (4) API (v3.1) app starts, I get the following exception:

Source: MapApp.OnUnhandledException()  Message: Mix spatial references are not supported. Parameter name: Envelope.Union    at ESRI.ArcGIS.Client.Geometry.Envelope.Union(Envelope extent)    at ESRI.ArcGIS.Client.LayerCollection.GetFullExtent()    at ESRI.ArcGIS.Client.Map.Layers_LayersInitialized(Object sender, EventArgs args)    at ESRI.ArcGIS.Client.LayerCollection.LayersInitializedHandler.Invoke(Object sender, EventArgs args)    at ESRI.ArcGIS.Client.LayerCollection.calculateLevelScheme(Boolean raiseInitialized)    at ESRI.ArcGIS.Client.LayerCollection.layer_OnInitialized(Object sender, EventArgs args)    at System.EventHandler`1.Invoke(Object sender, TEventArgs e)    at ESRI.ArcGIS.Client.Layer.OnInitialized(EventArgs e)    at ESRI.ArcGIS.Client.Layer.Initialize()    at ESRI.ArcGIS.Client.FeatureLayer.initialize()    at ESRI.ArcGIS.Client.FeatureLayer.featureLayerInfo_OutputReady(Object sender, EventArgs e)    at ESRI.ArcGIS.Client.FeatureService.FeatureLayerInfo.OnReady(EventArgs e)    at ESRI.ArcGIS.Client.FeatureService.FeatureLayerInfo.Execute_Completed(Object sender, DownloadStringCompletedEventArgs e)    at System.Net.WebClient.OnDownloadStringCompleted(DownloadStringCompletedEventArgs e)    at System.Net.WebClient.DownloadStringOperationCompleted(Object arg)

You can see from the stack trace that the exception originates inside an API class, not in my code. I never call Union() myself.

This happens at app startup. When it happens, I simply reload the page so that app startup starts over. it may happen a half dozen times in a row, then the app starts fine. Other times the app starts fine the first go.

The actual spatial references of my layers are all the same. But apparently sometimes they don't load correctly and appear different?

Any ideas on how I can handle this without my app completely blowing up?

Thanks, MC

markcheyne

got it. some of our map services are published with 'custom' SRs. In reality they are all the same SR, but some were published without setting the map document data frame to one of the canned SRs from ArcMap's picker, which assigns a version of our SR that has an WKID, instead just using the text version of the SR pulled from the ArcSDE layers, which are older and don't record their WKID and thus are 'custom'. These layers come across to the web APIs as if the layer SpatialReference.WKID is 0, while other services published with a WKID come across as nonzero, and the Map does not like that. I had code in the layer initialized event handler to check for these and set them to a nonzero WKID, but a bug with other logic in that handler meant that the check would get skipped depending on the order in which layers were initializing, which of course changes from one execution to the next due to the async nature of things.

whew!