If your Turnkey application does not start in IIS follow these guide lines to pinpoint problem area:

In the Turnkey web.config file, remove the section that makes errors route into the application:

<httpErrors errorMode="Detailed" >
</httpErrors>

If you do not replace this - some errors will be rerouted into the same situation that has the problem.

Make sure you have  

<system.web>
  <compilation debug="true" />

• Advanced settings for AppPool* (to consider)

Specific time same every day

allow overlap AppPool recycle

Idle time out action Suspend appPool (not terminate)

(To be completed)