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: 
**add** `<httpRuntime requestValidationMode="2.0"/>`  

 in **web.config**
and in **YourPage.aspx** set (ClientIDMode="Static" ValidateRequest="false") 

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

EXAMPLE: web.config

```
   <?xml version="1.0"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>
  <system.web>
    <httpRuntime requestValidationMode="2.0"/>
    <compilation debug="true" targetFramework="4.0">
      <assemblies>
        <add assembly="System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
      </assemblies>
    </compilation>

  </system.web>

  <connectionStrings>
    <add name="WT_ZadnjiEntities" connectionString="metadata=res://*/DAL.Model.csdl|res://*/DAL.Model.ssdl|res://*/DAL.Model.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=SATELLITE-PC;initial catalog=WT_Zadnji;integrated security=True;multipleactiveresultsets=True;App=EntityFramework&quot;" providerName="System.Data.EntityClient" />
  </connectionStrings>
</configuration>

```
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"/>;

```