CORS with WebAPI sometimes works, sometimes doesn't - asp.net-web-api

Question

I've used the following:
http://www.asp.net/web-api/overview/security/enabling-cross-origin-requests-in-web-api
As suggested here:
Enabling CORS with WebAPI PUT / POST requests?
to enable cross-origin AJAX requests in my project. Everything (POST / PUT / DELETE / GET) was working yesterday. Then I decided to add a new endpoint to my webAPI project, and this one is failing with:
> XMLHttpRequest cannot load http://localhost:24144/api/card. Origin
> http://localhost:11089 is not allowed by Access-Control-Allow-Origin.
In my WebApiConfig I've done this:
var cors = new EnableCorsAttribute("http://localhost:11089", "*", "*");
config.EnableCors(cors);
And my AJAX request, identical to others that are working, looks like this:
var updateCard = function (data) {
var options = {
url: apiEndpoint + 'card',
type: 'PUT',
async: true,
dataType: 'json',
data: data,
xhrFields: {
withCredentials: true
}
};
return $.ajax(options)
.done(function (response) {
toastr.success("Card Updated", "Success");
})
.fail(function (msg) {
toastr.error("Could not update card.", "Error");
});
}
};
Even if use the attribute directly on the method or controller that's failing, I get the same error:
[EnableCors(origins: "http://localhost:11089", headers: "*", methods: "*")]
Why would this be happening? I noticed that if I kill my webAPI solution while debugging, I get the same error in the client, but it usually only happens once and expected behavior resumes with the WebAPI project. This isn't a problem but maybe it's relevant.
If there's anything else you think I should provide here, let me know.
Update: Stack:
iisexpress.exe Information: 0 : Request, Method=OPTIONS, Url=http://localhost:24144/api/card, Message='http://localhost:24144/api/card'
iisexpress.exe Information: 0 : Message='Card', Operation=DefaultHttpControllerSelector.SelectController
iisexpress.exe Information: 0 : Message='Selected action 'UpdateCard(CardDto card)'', Operation=ApiControllerActionSelector.SelectAction
iisexpress.exe Information: 0 : Message='CorsPolicyProvider selected: 'System.Web.Http.Cors.EnableCorsAttribute'', Operation=AttributeBasedPolicyProviderFactory.GetCorsPolicyProvider
iisexpress.exe Information: 0 : Message='CorsPolicy selected: 'AllowAnyHeader: True, AllowAnyMethod: True, AllowAnyOrigin: False, PreflightMaxAge: null, SupportsCredentials: False, Origins: {http://localhost:11089}, Methods: {}, Headers: {}, ExposedHeaders: {}'', Operation=EnableCorsAttribute.GetCorsPolicyAsync
iisexpress.exe Information: 0 : Message='CorsResult returned: 'IsValid: True, AllowCredentials: False, PreflightMaxAge: null, AllowOrigin: http://localhost:11089, AllowExposedHeaders: {}, AllowHeaders: {accept,origin,content-type}, AllowMethods: {PUT}, ErrorMessages: {}'', Operation=CorsEngine.EvaluatePolicy
iisexpress.exe Information: 0 : Operation=CorsMessageHandler.SendAsync, Status=200 (OK)
iisexpress.exe Information: 0 : Response, Status=200 (OK), Method=OPTIONS, Url=http://localhost:24144/api/card, Message='Content-type='none', content-length=unknown'
iisexpress.exe Information: 0 : Request, Method=PUT, Url=http://localhost:24144/api/card, Message='http://localhost:24144/api/card'
iisexpress.exe Information: 0 : Message='Card', Operation=DefaultHttpControllerSelector.SelectController
iisexpress.exe Information: 0 : Message='App.Service.Controllers.CardController', Operation=DefaultHttpControllerActivator.Create
iisexpress.exe Information: 0 : Message='App.Service.Controllers.CardController', Operation=HttpControllerDescriptor.CreateController
iisexpress.exe Information: 0 : Message='Selected action 'UpdateCard(CardDto card)'', Operation=ApiControllerActionSelector.SelectAction
iisexpress.exe Information: 0 : Operation=AuthorizeAttribute.OnAuthorization
iisexpress.exe Information: 0 : Message='Value read='App.Repository.Models.Dtos.CardDto'', Operation=JQueryMvcFormUrlEncodedFormatter.ReadFromStreamAsync
iisexpress.exe Information: 0 : Message='Parameter 'card' bound to the value 'App.Repository.Models.Dtos.CardDto'', Operation=FormatterParameterBinding.ExecuteBindingAsync
iisexpress.exe Information: 0 : Message='Model state is valid. Values: card=App.Repository.Models.Dtos.CardDto', Operation=HttpActionBinding.ExecuteBindingAsync
A first chance exception of type 'System.Data.Entity.Validation.DbEntityValidationException' occurred in EntityFramework.dll
iisexpress.exe Information: 0 : Message='Will use same 'JsonMediaTypeFormatter' formatter', Operation=JsonMediaTypeFormatter.GetPerRequestFormatterInstance
iisexpress.exe Information: 0 : Message='Selected formatter='JsonMediaTypeFormatter', content-type='application/json; charset=utf-8'', Operation=DefaultContentNegotiator.Negotiate
iisexpress.exe Information: 0 : Message='Action returned 'StatusCode: 500, ReasonPhrase: 'Internal Server Error', Version: 1.1, Content: System.Net.Http.ObjectContent`1[[System.Exception, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]], Headers:
{
Content-Type: application/json; charset=utf-8
}'', Operation=ReflectedHttpActionDescriptor.ExecuteAsync
iisexpress.exe Information: 0 : Operation=ApiControllerActionInvoker.InvokeActionAsync, Status=500 (InternalServerError)
iisexpress.exe Information: 0 : Operation=CardController.ExecuteAsync, Status=500 (InternalServerError)
iisexpress.exe Information: 0 : Message='CorsPolicyProvider selected: 'System.Web.Http.Cors.EnableCorsAttribute'', Operation=AttributeBasedPolicyProviderFactory.GetCorsPolicyProvider
iisexpress.exe Information: 0 : Message='CorsPolicy selected: 'AllowAnyHeader: True, AllowAnyMethod: True, AllowAnyOrigin: False, PreflightMaxAge: null, SupportsCredentials: False, Origins: {http://localhost:11089}, Methods: {}, Headers: {}, ExposedHeaders: {}'', Operation=EnableCorsAttribute.GetCorsPolicyAsync
iisexpress.exe Information: 0 : Message='CorsResult returned: 'IsValid: True, AllowCredentials: False, PreflightMaxAge: null, AllowOrigin: http://localhost:11089, AllowExposedHeaders: {}, AllowHeaders: {}, AllowMethods: {}, ErrorMessages: {}'', Operation=CorsEngine.EvaluatePolicy
iisexpress.exe Information: 0 : Operation=CorsMessageHandler.SendAsync, Status=500 (InternalServerError)
iisexpress.exe Information: 0 : Response, Status=500 (InternalServerError), Method=PUT, Url=http://localhost:24144/api/card, Message='Content-type='application/json; charset=utf-8', content-length=unknown'
iisexpress.exe Error: 0 : Operation=JsonMediaTypeFormatter.WriteToStreamAsync, Exception=Newtonsoft.Json.JsonSerializationException: Error getting value from 'Stage' on 'System.Data.Entity.DynamicProxies.Side_F7B85DBC8AA69F5AAA5ACCA92A66F2763E57D4D2046F02AC7EE6064A3409DE42'. ---> System.ObjectDisposedException: The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.
at System.Data.Objects.ObjectContext.EnsureConnection()
at System.Data.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
at System.Data.Objects.ObjectQuery`1.Execute(MergeOption mergeOption)
at System.Data.Objects.DataClasses.EntityReference`1.Load(MergeOption mergeOption)
at System.Data.Objects.DataClasses.RelatedEnd.Load()
at System.Data.Objects.DataClasses.RelatedEnd.DeferredLoad()
at System.Data.Objects.Internal.LazyLoadBehavior.LoadProperty[TItem](TItem propertyValue, String relationshipName, String targetRoleName, Boolean mustBeNull, Object wrapperObject)
at System.Data.Objects.Internal.LazyLoadBehavior.<>c__DisplayClass7`2.<GetInterceptorDelegate>b__2(TProxy proxy, TItem item)
at System.Data.Entity.DynamicProxies.Side_F7B85DBC8AA69F5AAA5ACCA92A66F2763E57D4D2046F02AC7EE6064A3409DE42.get_Stage()
at GetStage(Object )
at Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(Object target)
--- End of inner exception stack trace ---
at Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(Object target)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CalculatePropertyValues(JsonWriter writer, Object value, JsonContainerContract contract, JsonProperty member, JsonProperty property, JsonContract& memberContract, Object& memberValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IWrappedCollection values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IWrappedCollection values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeISerializable(JsonWriter writer, ISerializable value, JsonISerializableContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeISerializable(JsonWriter writer, ISerializable value, JsonISerializableContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value)
at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value)
at Newtonsoft.Json.JsonSerializer.Serialize(JsonWriter jsonWriter, Object value)
at System.Net.Http.Formatting.JsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content)
at System.Net.Http.Formatting.JsonMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext)
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
at System.Web.Http.Tracing.ITraceWriterExtensions.<TraceBeginEndAsyncCore>d__33.MoveNext()
iisexpress.exe Information: 0 : Message='Will use same 'JsonMediaTypeFormatter' formatter', Operation=JsonMediaTypeFormatter.GetPerRequestFormatterInstance
iisexpress.exe Information: 0 : Message='Selected formatter='JsonMediaTypeFormatter', content-type='application/json; charset=utf-8'', Operation=DefaultContentNegotiator.Negotiate
iisexpress.exe Information: 0 : Operation=JsonMediaTypeFormatter.WriteToStreamAsync
iisexpress.exe Information: 0 : Operation=CardController.Dispose

Answer 1

In case anyone else runs into this and happens to be using Unit Of Work and CORS from WebAPI2 with EF (ha) -
I had a lazily-loaded property that was not available when the Update method was executing. I don't know why the error thrown was inaccurate, but the stack trace pointed me in the right direction:
Error getting value from 'Stage' on
'System.Data.Entity.DynamicProxies.Side_F7B85DBC8AA69F5AAA5ACCA92A66F2763E57D4D2046F02AC7EE6064A3409DE42'.
---> System.ObjectDisposedException: The ObjectContext instance has been disposed and can no longer be used for operations that require a
connection.

Answer 2

If you are using IIS 7.5 or below use this config
<system.webServer>
<handlers>
<remove name="OPTIONSVerbHandler"/>
</handlers>
</system.webServer>
Or if you are using IIS 8 or above
<system.webServer>
<handlers>
<remove name="OPTIONS"/>
</handlers>
</system.webServer>
Hope this help