Ssl – IIS 503 Service unavailable when using SSL

503-erroriis-8.5ssl

I've setup an https binding for my site in IIS but I'm getting a 503 Service Unavailable error whenever I try to hit the endpoint.

What's weird is I can access the site without issue over port 80.

The application pool is started and I can't find any errors in the windows logs.

What's the best way to go about debugging this issue?

Best Answer

I'd do the following steps to troubleshoot such scenarios:

Turn on display of detailed error messages

  1. Open the machine.config file located in: %windir%\Microsoft.NET\Framework\\CONFIG
  2. Remove the line <deployment retail="true" /> within the <system.web> section, or change it to the default value of "false".
  3. If systems are 64-bit, do the same for the machine.config located in: %windir%\Microsoft.NET\Framework64\\CONFIG

Turn on debug mode on your Web.config

Browse to and open the web.config file pertaining to the server or specific application that has been configured. Modify values in these tags: <compilation debug>, <customErrors>, and <httpErrors>:

<configuration>  
    <system.web>  
        <compilation debug="true" />   <!-- this is the default value -->
        <customErrors mode="RemoteOnly" /> <!-- this is the default value. Alternatively, you can also set it to <customErrors mode="On" /> -->
        <httpErrors errorMode="DetailedLocalOnly"> <!-- this is the default value -->
    </system.web>  
</configuration>

Browse your ASP site In IIS Manager, right click your site then select "Manage Application" > "Browse". Your Internet Explorer browser should popup. If there are any SSL related errors, just click on "Continue to this website".

Error messages, if any, should appear here.

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