We have got two separate servers running DNN version 9.01.01.

They both are configured the same in IIS with Custom Error Pages turned off.
The web.config is set to:

```
<customErrors mode="off"/>

```

We are trying to test and go to a page which does not exist which should give a 404 Error page but instead, it goes to a 503 Error Page (Service Unavailable). When I look at the DNN Admin Logs it says the that it is trying to go to a 404 error page.

[![enter image description here](https://i.stack.imgur.com/N22U6.jpg)](https://i.stack.imgur.com/N22U6.jpg)

[![enter image description here](https://i.stack.imgur.com/GlngY.jpg)](https://i.stack.imgur.com/GlngY.jpg)

I noticed that when I select a non-specified page in the DNN Settings under the Behaviour Tab, it then gives a different error:

[![enter image description here](https://i.stack.imgur.com/X4ppg.jpg)](https://i.stack.imgur.com/X4ppg.jpg)

From this information, I suspect it is a DNN 9.1.1 bug?

I found a previous bug which was present in earlier DNN versions:
<https://dnntracker.atlassian.net/browse/DNN-8611?jql=summary%20~%20%22503%20error>*%22%20OR%20description%20~%20%22503%20error*%22%20ORDER%20BY%20lastViewed%20DESC

I also found this DNN post:

<https://www.dnnsoftware.com/forums/threadid/538218/scope/posts/getting-503-error-instead-of-404-page>

[![enter image description here](https://i.stack.imgur.com/3iRva.jpg)](https://i.stack.imgur.com/3iRva.jpg)