01332 947465 info@horizon-it.co.uk

Windows Server IIS – Windows Process Activation Service (WAS) will not start.

So here at Horizon IT we run many web sites on our web servers, and after applying a recent Windows Update the IIS WWW, World Wide Web Publishing Service would not start.
It was saying the dependent service, Windows Process Activation Service (WAS), was not running, so then we tried to start that.
When we did that we had the usual cryptic Microsoft error:

“The Windows Process Activation Service encountered an error trying to read configuration data with AppHostProvider. The error message is: Bad Data. The data field contains the error number.”

Of course the error number means nothing!

So it’s 23:30 and we have 100 sites down and a server services that will not start.
We dive into Google and start hunting, after 45 minutes, with no success, we were about to consider rolling back the server to a previous back.
Then we found the article that changed the game!

We run a Plesk install on our server and earlier that day we had added a new web site for hosting.
We do that all the time, so nothing to worry about there….  Or maybe there is!!
It turns out that the site we added was the 101 site on the server, and guess what, there’s a buried setting that only allows WAS service to start if there are 100 sites in IIS or less!

Now we know that like us you a) Are baffled by such an arbitrary limit, and b) Stunned they couldn’t provide a meaningful error message.

So how do you fix it?
This link will give you the details:

Basically you:

  1. Open IIS Manager
  2. Select your IIS Server, then Configuration Editor
  3. Select the section system.applicationHost/webLimits.
  4. Change the value of dynamicRegistrationThreshold to a value greater than 100
  5. Start Windows Process Activation Service (WAS) service,
  6. Start WWW, World Wide Web Publishing Service.
  7. BOOM! sites up and running.






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