Question: I'm occasionaly getting the following popup from an AJAX.NET application

```
Sys.WebForms.PageRequestManagerServerErrorException: An Unknown error occurred while processing the request on the server. The status code returned from the server was: 12031
```

From the [Microsoft kb](http://support.microsoft.com/kb/193625) that status code indicates a ERROR\_INTERNET\_CONNECTION\_RESET, but it doesn't state what was the underlying issue the triggered the error in the first place.

How can I log/trace/etc the underlying error that generated the popup?

Answer: 
I've got this error in UpdatePanel with autopostback Dropdown after big delay (>20 min) between change dropdown selection.

Try increase session timeout in web.cofig. For example:

```
<sessionState mode="InProc" cookieless="true" timeout="720"/>;

```
sometimes the error occurs if you have added a server SSL certificate(https).If the certificate is not valid it will give this error.