web.config error
<?xml version="1.0"?>
<configuration>
<connectionStrings>
    <add name="ConnectionString"
             connectionString="Data Source=.SQLEXPRESS;AttachDbFilename=|DataDirectory|ASPNETDB.MDF;Integrated Security=True;User Instance=True"
             providerName="System.Data.SqlClient"/>
</connectionStrings>
<system.web>
    <customErrors mode="Off"/>
    <compilation debug="true"/>
</system.web>
<pages>
    <namespaces>
        <clear/>
        <add namespace="System"/>
        <add namespace="System.Collections"/>
        <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>
<membership>
    <providers>
        <clear/>
        <add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="LocalSqlServer" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10" applicationName="/"/>
    </providers>
</membership>
<profile>
    <providers>
        <clear/>
        <add name="AspNetSqlProfileProvider" type="System.Web.Profile.SqlProfileProvider" connectionStringName="LocalSqlServer" applicationName="/"/>
    </providers>
</profile>
<authentication mode="Forms">
    <forms loginUrl="login.aspx" defaultUrl="Default.aspx"/>
</authentication>
<authorization>
    <allow users="*"/>
</authorization>
<location path="PhotoAdmin">
    <system.web>
        <authorization>
            <deny users="?"/>
        </authorization>
    </system.web>
</location>
<system.net>
    <mailSettings>
      <smtp from="some@example.com">
        <network host="relay-hosting.example.net" password="" userName=""/>
      </smtp>
    </mailSettings>
</system.net>
</configuration>

<compilation debug="true" targetFramework="4.0" />