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Web.Config Error While running asp.net website on Mobile

I have developed a website in asp.net and hosted it on server. It works fine with computer's but it do not run on mobile. The web.config error occurs every time.Web.config Error Occurs Every Time.

In Web.Config file do as below
<configuration>
<system.web>
<customErrors defaultRedirect="GenericError.htm"
mode="RemoteOnly">
<error statusCode="500"
redirect="InternalError.htm"/>
</customErrors>
</system.web>
</configuration>
it for the Un-handeled exception thrown when use browsing your web application. if you dont set that flag user will receive full stackstrace of error which user dont want. so it better you set the flag to On or Remoteonly in production environment.
On-Specifies that custom errors are enabled. If no defaultRedirect attribute is specified, users see a generic error. The custom errors are shown to the remote clients and to the local host.
Off-Specifies that custom errors are disabled. The detailed ASP.NET errors are shown to the remote clients and to the local host.
RemoteOnly-Specifies that custom errors are shown only to the remote clients, and that ASP.NET errors are shown to the local host. This is the default value.
Read more : https://msdn.microsoft.com/en-us/library/h0hfz6fc(v=vs.100).aspx

Windows Authentication .Net Core 2.0 Show Username Without Security Prompt

I created a brand new Asp.Net Core 2.0 web mvc application with windows authentication enabled.
If I immediately hit play it prompts me for user credentials which is not what I want. If I hit cancel it then redirects me to a 401.2 unauthorized error screen with the following error:
"You are not authorized to view this page due to invalid
authentication headers."
When I then stop the application and enable anonymous authentication on the project and hit play again, it runs the application successfully but will not display my username. #User.Identity.Name returns empty string.
How do I get around the security prompt while still being able to display my username?
In the .NET Framework, I would use this in the web.config file along with anonymous authentication = true and it would work the way I want:
<authentication mode="Windows" />
<authorization>
<deny users="?" />
</authorization>
I am using Visual Studio 15.4.1.

I think that the <authentication> tag is related to ASP.NET, and not IIS. In ASP.NET Core, the System.Web pipeline doesn't run.
I've had success in implementing Windows authentication with ASP.NET Core by using the following configuration in the web.config
<configuration>
<system.webServer>
<security>
<authentication>
<anonymousAuthentication enabled="false" />
<windowsAuthentication enabled="true" />
</authentication>
</security>
</system.webServer>
</configuration>
The <system.webServer> section is the one getting modified when you change the authentication settings through IIS Manager.
Edit after Ben's first comment
Sorry, I had misread part of your initial message, and thought that you were trying to deploy your application in IIS.
It looks like Windows Authentication is set up correctly since you get prompted for credentials. What I don't understand is why you get prompted. I'm using IE11, Edge and Chrome, and they all know how to send Windows credentials without prompting me.
What browser are you using when doing your test? Could you try with the ones I listed above?

Getting error while hosting WCF service when add <trust level="Full" />

I am trying to host WCF service in "hostgator". I want to set Trust level because I am getting security permission error.
When I set Trust Level in web.config, I am getting an error.
web.config:
<location allowOverride="true">
<system.web>
<compilation debug="true" targetFramework="4.5.2"/>
<identity impersonate="false" />
<authentication mode="None" />
<httpRuntime maxUrlLength="1024" relaxedUrlToFileSystemMapping="true"/>
<customErrors mode="Off"></customErrors>
<securityPolicy>
<trustLevel name="Full" policyFile="internal"/>
</securityPolicy>
</system.web>
</location>
Error:
An application error occurred on the server. The current custom error
settings for this application prevent the details of the application
error from being viewed remotely (for security reasons). It could,
however, be viewed by browsers running on the local server machine.
Can anybody suggest a way to solve this?
enter image description here

Per HostGator FAQ you must run in partial trust using their shared hosting:
No. The applications must be published in Medium Trust in order to run
on the Windows Shared Server.
You're not going to be able to use the SDK in a medium trust environment from what I've read. As Dynamics CRM 2016 expands its support for its REST API that may become an option for you.

Publishing ASP.NET MVC to Azure -- works locally but not on Azure

I've been investigating this thing for hours but couldn't understand what's the problem causing this behavior.
I have built a simple ASP.NET MVC app to upload and delete photos from a predefined container on the Azure Storage Server.
It works perfectly when I run the application on my machine, locally.
Also, it works perfectly when I run this on my machine but the Data service is located on Azure.
But, when Publishing the application to Azure, surfing to this website runs to this uninformative error:
Server Error in '/' Application.
Runtime Error
Description: An application error occurred on the server. The current
custom error settings for this application prevent the details of the
application error from being viewed remotely (for security reasons).
It could, however, be viewed by browsers running on the local server
machine.
Details: To enable the details of this specific error message to be
viewable on remote machines, please create a tag within
a "web.config" configuration file located in the root directory of the
current web application. This tag should then have its
"mode" attribute set to "Off".
<!-- Web.Config Configuration File -->
<configuration>
<system.web>
<customErrors mode="Off"/>
</system.web>
</configuration>
Notes: The current error page you are seeing can be replaced by a
custom error page by modifying the "defaultRedirect" attribute of the
application's configuration tag to point to a custom
error page URL.
<!-- Web.Config Configuration File -->
<configuration>
<system.web>
<customErrors mode="RemoteOnly" defaultRedirect="mycustompage.htm"/>
</system.web>
</configuration>
This doesn't tell me anything, also - nothing like this happens when running on my machine with Visual Studio.
If you have any idea what's going on here I'd really appreciate your help, thanks.

Getting "The WebResource.axd handler must be registered in the configuration to process this request." error

I'm getting this error while running my ASP.NET app on IIS7. I've tried doing what it says to do but it doesn't help.
The WebResource.axd handler must be
registered in the configuration to
process this request.
> <!-- Web.Config Configuration File -->
>
> <configuration>
> <system.web>
> <httpHandlers>
> <add path="WebResource.axd" verb="GET" type="System.Web.Handlers.AssemblyResourceLoader" validate="True" />
> </httpHandlers>
> </system.web>
> </configuration>
I'm using a little bit of AJAX which is what I think is causing the issue. Has anyone encountered this before?

I figured it out so I'm posting it here for search reasons. It is a bug in ASP.NET and it has to do with having ColdFusion installed. Microsoft hasn't yet released a fix.
There are two ways to fix this.
Change the AppPool in IIS7 to "Classic .NET AppPool". I'm not sure of any implications with this setting.
Remove all the references to ColdFusion from your applicationHost.config file in system32\inetsrv\config.

ColdFusion installs a global wildcard handler mapping which apparently overrides many of the standard .NET handlers. The solutions mentioned work just fine, but if you can't switch to Classic Mode and don't want to screw with your ColdFusion installation, you can remove the inherited handler mapping at the individual site level.
To do this, go to the site in question in IIS, double-click on "Handler Mappings" under the "IIS" section, and find the handler named something like "AboMapperCustom-XXXXXX" with "*" for the Path. Select the entry and click "Remove" in the sidebar. This will only remove the mapping for your application, so it won't break any existing CF sites on the server.

In IIS7 you need to add the <httpHandler> section to <system.webServer> instead of <system.web>. Here is an example.

I got this error after carelessly copying my app's web.config between a pair of clustered servers, which overwrote the tag:
<system.webServer>
<handlers>
<remove name="AboMapperCustom-XXXXXXXX" />
</handlers>
</system.webServer>
with
<system.webServer>
<handlers>
<remove name="AboMapperCustom-YYYYYYYY" />
</handlers>
</system.webServer>
Locating the proper ID as per Josh's response and correcting the tag fixed it, but more importantly, will presumably keep that handler mapping from sneaking back in.

The issue happened to me on new Windows 2016 server where ASP.NET 4.6 was not installed. After installation everything got fixed.
Steps
- Run Server Manager
- Manage > Add Roles and Features
- Server Roles
- Web Server (IIS) > Web Server > Application Development > ASP.NET 4.6

I had this problem and that reason was incompatibility between Coldfusion and some configurations of ASP.NET applications when IIS App pool is in integrated mode. Coldfusion must be disable .