I am developing an ASP.NET Web API v2 application. My application works fine from my DEV machine but when I go to deploy it to my server it gives the following errors.
The following errors occurred while attempting to load the app.
- No assembly found containing an OwinStartupAttribute.
- No assembly found containing a Startup or [AssemblyName].Startup class.
To disable OWIN startup discovery, add the appSetting owin:AutomaticAppStartup with a value of "false" in your web.config.
To specify the OWIN startup Assembly, Class, or Method, add the appSetting owin:AppStartup with the fully qualified startup class or configuration method name in your web.config.
After searching Google, SO, and other sites I found adding a default Startup.cs class to my project fixed the issue. The problem is I don't know how.
What did adding Startup.cs do?
Why would my app compile and run on my development machine without Startup.cs?
This seems to involve OWIN but I was not even aware I was making use of any OWIN features.
This is most likely due to the way OWIN searches for its entry point (Startup class). In your dev environment you probably have a DLL in the project folder that has an OWIN Startup class. That dll is not being deployed as part of the deployment step and therefore doesn't exist in your deployed location.
Another posibility, along the same lines, is you're using .config transformations and you have defined a Startup class in your DEV config but not in your deployed config.
<appSettings>
<add key="owin:appStartup" value="StartupDemo.ProductionStartup" />
</appSettings>
OWIN Startup Class Detection might be informative.
MVC5 uses OWIN pipeline by default so it's "under the hood". Perhaps you migrated from a previous MVC site and that's why the Startup class was missing?
Cheers!
Related
How can I get a unit test project in a (VS2015) solution for a WCF web service to use the same web.config file for its own app.config? I don't want to have to replicate all the settings that are in web.config in my app.config (and have to remember to keep them in sync). Thanks.
I was able to shift the relevant settings to a separate config file using this method. One thing to remember is that paths are relative to the WhateverTests\bin\Debug folder when referring to the other config file in the Whatever project.
I have just installed Visual Studio 2013, created an MVC Web Application project and noticed a new file in the project template called Startup.cs.
What is this, how is this different from Global.asax.cs and are there any good best practices on what to use this for?
Every OWIN application has a startup class where you specify components for the application pipeline.
If you start a new Visual Studio project, you'll see pieces of OWIN in it.
OWIN is a specification that defines an API for framework and servers to cooperation.
The point of OWIN is to decouple server and application.
For example, ASP.NET Identity uses OWIN security, SignalR self hosting uses OWIN hosting, and etc., the examples all use OWIN,
therefore they all need to have a startup class, that is defined in "Startup.cs" file.
The Global.asax, the ASP.NET application file, is an optional file that contains code for responding
to application-level events raised by ASP.NET or by HttpModules.
For more details:
OWIN
http://www.asp.net/aspnet/overview/owin-and-katana
Global.asax
http://msdn.microsoft.com/en-us/library/1xaas8a2(v=vs.71).aspx
You can find more ideas about why OWIN in the following article:
http://www.asp.net/aspnet/overview/owin-and-katana/an-overview-of-project-katana
The file seems to be related to SignalR. Quoting the VS 2013 release notes:
Built on OWIN
SignalR 2.0 is built completely on OWIN (the Open Web Interface for
.NET). This change makes the setup process for SignalR much more
consistent between web-hosted and self-hosted SignalR applications,
but has also required a number of API changes.
MapHubs and MapConnection are now MapSignalR
For compatibility with OWIN standards, these methods have been renamed
to MapSignalR. MapSignalR called without parameters will map all hubs
(as MapHubs does in version 1.x); to map individual
PersistentConnection objects, specify the connection type as the type
parameter, and the URL extension for the connection as the first
argument.
The MapSignalR method is called in an Owin startup class. Visual
Studio 2013 contains a new template for an Owin startup class; to use
this template, do the following:
Right-click on the project
Select Add, New Item...
Select Owin Startup class. Name the new class Startup.cs.
In a Web application, the Owin startup class containing the MapSignalR
method is then added to Owin's startup process using an entry in the
application settings node of the Web.Config file, as shown below.
In a Self-hosted application, the Startup class is passed as the type
parameter of the WebApp.Start method.
The Startup class is the convention that Katana/OWIN looks for to initialize the pipeline. When your app starts, the code inside of the Configuration function is run to set up the components that'll be used. In the MVC 5 templates, it's used to wire up the authentication middleware which is all built on top of OWIN.
If you want to use dependency injection with OWIN, check out this project on GitHub: DotNetDoodle.Owin.Dependencies
Im currently using Umbraco 4.11 that is integrated to an asp.net mvc 3 application. Im trying to reference a wcf service in the umbraco project by selecting Add Service Reference in visual studio but I can not seem to access the service library once it is added. I tried to look into the object view browser and I couldn't find the object namespace for the wcf service. Am I missing something? Is this method of consuming wcf service in umbraco possible? I prefer not to use a separate project that uses a user control to access the wcf service since it seems to be tedious to do.
There is a warning when adding a service reference:
Cannot import wsdl:portType
Detail: An exception was thrown while running a WSDL import extension: System.ServiceModel.Description.DataContractSerializerMessageContractImporter
Error: Could not load file or assembly 'umbraco, Version=1.0.4090.38017, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.
You may want to setup the service reference in a separate project, then migrate the dll and the web.config settings. Then you should be able to access your web service via razor after adding using statements.
The problem is that the code file for the service isn't being generated because of a conflict with umbraco. You could alternatively generate the code file manually using svcutil.exe.
We have an MVC3 application deployed on IIS 7.5, and now need to deploy another app in a subdirectory of the main one. After running into Web.config inheritance conflict we tried to wrap the system.web section of the parent app's config file in <location path="." inheritInChildApplications="false">, as recommended in the accepted answer to web.config - how to prevent all inheritance, but we're getting an error:
InheritInChildApplications cannot be set to "false" if the location
path is referring to machine.config or the root web.config.
What are we doing wrong?
There was a known bug in 51Degrees.mobi component which accessed its config in a way that caused the application to crash when inheritInChildApplications property was used in the config file.
Apparently it has been fixed in newer library version as described here.
i have a a new silverlight solution in visual studio. i have created a silverlight class library to share common functionality. this class library has a service reference and so it has a ServiceReferences.ClientConfig file. the problem is if i create a project in this solution and add a reference to the class library it seems that i need a ServiceReferences.ClientConfig in this individual project. if i copy and paste the ServiceReferences.ClientConfig file from the class library to the project, everything works fine. if i do not i get the error below. doesnt this defeat the purpose of sharing this service reference in a class library? i want to be able to change where the service reference points to (debug machine / production machine) easily in one place. what can i do? is there another way i'm missing? Thank you.
Cannot find 'ServiceReferences.ClientConfig' in the .xap application package. This file is used to configure client proxies for web services, and allows the application to locate the services it needs. Either include this file in the application package, or modify your code to use a client proxy constructor that specifies the service address and binding explicitly. Please see inner exception for details. >
The config for the class library is not packaged into the .xap file. Without that configuration, the service reference cannot be properly configured.
doesnt this defeat the purpose of sharing this service reference in a class library?
Not really. The bulk of the "service reference" is the code in the class library. This is what you are sharing. Since a xap (or exe and web app) has only one config file, you must have the ServiceReferences.ClientConfig in the application's config file.
I am not aware of a mechanism to copy some important bits from the config file of a class library to the application config file during a build.