Deploying website: 500 - Internal server error

Question

I am trying to deploy an ASP.NET application. I have deployed the site to IIS, but when visiting it with the browser, it shows me this:

Server Error

500 - Internal server error.

There is a problem with the resource you are looking for, and it cannot be displayed.

After fiddling around with the web.config, I got:

The page cannot be displayed because an internal server error has occurred.

How can I see the actual issue behind this server error?

Answer 1

For IIS 8

<system.web>
   <customErrors mode="Off" />
</system.web>
<system.webServer>
   <httpErrors existingResponse="PassThrough" errorMode="Detailed">
</system.webServer>

Turn off IIS8 custom errors by Raul

Answer 2

If you are using IIS 8.5 it may be that you need to change the ApplicationPool ID setting from ApplicationPoolId to NetworkService

Right click the Application Pool in question, click on "Advanced Settings" and then scroll down to ID - it will probably be set to ApplicationPoolIdentity. Click the button (..) and select NetworkService from the dropdown list instead.

Also make sure that if it is a .NET 2.0 application that you are not referencing the 4.0 framework in your App Pool.

Answer 3

For me, the following code in the web.config was the culprit. When I removed it, the web site worked fine.

  <staticContent>
    <mimeMap fileExtension=".mp4" mimeType="video/mp4" />
  </staticContent>

Answer 4

In my case, I put a mistake in my web.config file. The application key somehow was put under the <appSettings> tag. But I wonder why it doesn't display a configuration error. The error 500 is too generic for investigating the problem.

Answer 5

In addition to the other suggestions, make sure to change the existingResponse attribute of the httpErrors node to Auto from Replace, or to remove that property entirely.

<httpErrors existingResponse="Replace" />
                              ^^^^^^^ not going to work with this here

Answer 6

I was pulling my hair out over this issue. Making sure the following entry was in the root web.config file fixed it for me:

<configuration>
  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />
  </system.webServer>
</configuration>

Remember that you have to add this to the existing XML elements, if they're already there. You can't just add at the end of the file, because you can't have multiple copies of any element.