i get 500 - Internal server error from my asp.NET wab site

i have uploaded some ASP.NET web pages on the server (freeasphost.net) , the default page an the other page work correctly, but today when i take a visite to my web site (the default page) i got error :

500 - Internal server error.

There is a problem with the resource you are looking for, and it cannot be displayed.

i searched for some solutions on the internet, i have found that the error is related to the web.config file configuration, this is my web.config file:

<?xml version="1.0"?>
<configuration>
  
   <system.webServer>
        <httpErrors errorMode="Detailed" />
    </system.webServer>

  
  <system.web>
  <customErrors mode="Off"/>
        <compilation debug="true"/>
   
   

    <pages controlRenderingCompatibilityVersion="3.5" clientIDMode="AutoID">
      <namespaces>
        <clear/>
        <add namespace="System"/>
        <add namespace="System.Collections"/>
        <add namespace="System.Collections.Generic"/>
        <add namespace="System.Collections.Specialized"/>
        <add namespace="System.Configuration"/>
        <add namespace="System.Text"/>
        <add namespace="System.Text.RegularExpressions"/>
        <add namespace="System.Web"/>
        <add namespace="System.Web.Caching"/>
        <add namespace="System.Web.SessionState"/>
        <add namespace="System.Web.Security"/>
        <add namespace="System.Web.Profile"/>
        <add namespace="System.Web.UI"/>
        <add namespace="System.Web.UI.WebControls"/>
        <add namespace="System.Web.UI.WebControls.WebParts"/>
        <add namespace="System.Web.UI.HtmlControls"/>
      </namespaces>
    </pages>
  </system.web>
 
</configuration>