User915387828 posted
Hi sicardg,
Please disable "Show Friendly HTTP error messages" of IE and enable
"detailed errors for remote clients" in your ASP.NET application. After running the application please observe what errors are being thrown.
To turn off ASP.NET custom errors, place the following in your web.config:
<system.web>
<customErrors mode=”Off” />
</system.web>
And please use Event Viewer. This will show you the error which IIS reports. The second thing that I would do is to look at the IIS Log files.