WCF on .Net 4.x ReST Service with IIS 7 or 8 = HTTP Error 404.17

So my newly created WCF ReST service (or webHttp service, as MS more accurately like to call it) runs fine in Visual Studio 2012, using IIS Express. But when I switch to IIS proper (in my case, IIS8 on Windows 8) I get:

HTTP Error 404.17 - Not Found
The requested content appears to be script and will not be served by the static file handler.

Most so-far extant posts on how to fix this, refer to how to fix it for .Net 3 on Windows before Win8: Use "%WINDIR%\Microsoft.Net\Framework\v3.5\Windows Communication Foundation\ServiceModelReg.exe" to register or to repair registration of WCF components. (The other gotcha being, having the right AppPool settings for .Net version & for 32 vs. 64 bit).
This doesn't work for Windows 8 / .Net 4.X. Instead you must open the control panel "Turn Windows Features On or Off" and tick the box for Http activation:

Windows Features - Windows 8 - Net45 - WCF - Http Activation Tickbox
Windows Features - Windows 8 - Net45 - WCF - Http Activation

Which should fix the issue after a couple of minutes.

Asp.net / IIS7 : System.BadImageFormatException: Could not load file or assembly

You have something like this:


Server Error in '/Vendorapplication' Application.
Could not load file or assembly 'Oracle.DataAccess' or one of its dependencies. An attempt was made to load a program with an incorrect format.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.BadImageFormatException: Could not load file or assembly 'Oracle.DataAccess' or one of its dependencies. An attempt was made to load a program with an incorrect format.
Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

It's because you are trying to run 32 bit dlls on a 64 bit system. Fix it in IIS manager by changing the advanced settings on you application pool to enable 32 bit applications. Or create a new app pool specifically for them.

Alex James Brown has a nice picture: change app pool to 32 bit