IIS 10.0 Detailed Error: mimeMap - asp.net

Question

Hello so I'm pretty new to using IIS and Visual Studio but I've managed to launch one website on IIS but when I try to launch this one I get this error across the page:
Error message:
Cannot add duplicate collection entry of type 'mimeMap' with unique key attribute 'fileExtension' set to '.mp4'
There's a section that reads Config Error:so here is my web.config file:
<?xml version="1.0"?>
<configuration>
<appSettings>
<add key="DetailLogging" value="True"/>
<add key="LoggingConfigFile" value="log4net.config"/>
<add key="DatabaseConnectionString" value="Integrated Security=True; MultipleActiveResultSets=True; Data source=.\SQLEXPRESS; Initial Catalog=WebEvaluation" />
<add key="Email" value="***********************"/>
<add key="SupportEmailID" value="*************************"/>
<add key="ForgotPasswordEmailSubject" value="Butterfly Scheme e-Certification Admin Console - Password Request"/>
<add key="WelcomeMailSubject" value="Butterfly Scheme e-Certification Admin Console"/>
<add key="PasswordChangedMailSubject" value="Butterfly Scheme e-Certification Admin Console - Password Changed"/>
<add key="PasscodeDeleteMailSubject" value="Passcode delete notification - "/>
<add key="Host" value="***********"/>
<add key="PortNo" value="25"/>
<add key="Password" value="***********"/>
<add key="SiteURL" value="***********************************"/>
<add key="RecordsPerPage" value="20" />
<add key="PasscodeCreateMailSubject" value="Butterfly Scheme e-Certification Passcode List created for : "/>
<add key ="XlsConnectionString" value="Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0}; Extended Properties='Excel 8.0;IMEX=1'"/>
<add key ="XlsxConnectionString" value="Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0}; Extended Properties='Excel 8.0;'"/>
</appSettings>
<system.web>
<compilation debug="true" targetFramework="4.0">
<assemblies>
<add assembly="System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=******************"/>
<add assembly="System.Web.Extensions.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=******************"/>
<add assembly="System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
</assemblies>
</compilation>
<httpRuntime requestValidationMode="2.0" maxRequestLength="2097151"
executionTimeout="900"/>
<sessionState mode="InProc" timeout="20"/>
</system.web>
<system.webServer>
<modules runAllManagedModulesForAllRequests="true"/>
<staticContent>
<mimeMap fileExtension=".mp4" mimeType="video/mp4"/>
<mimeMap fileExtension=".m4v" mimeType="video/m4v"/>
<mimeMap fileExtension=".3gp" mimeType="video/3gpp"/>
</staticContent>
<security>
<requestFiltering>
<requestLimits maxAllowedContentLength="2147482624"/>
</requestFiltering>
</security>
</system.webServer>
</configuration>

Answer 1

You could add something like this:
<remove fileExtension=".mp4" />
Or, since the MP4 mime type seems to be already present in the roots configuration file, simply omit the whole line:
<mimeMap fileExtension=".mp4" mimeType="video/mp4"/>
If you really want to be sure that the extensions you seem to require are present, this could be a replacement for the staticContent tag:
<staticContent>
<remove fileExtension=".mp4" />
<remove fileExtension=".m4v" />
<remove fileExtension=".3gp" />
<mimeMap fileExtension=".mp4" mimeType="video/mp4"/>
<mimeMap fileExtension=".m4v" mimeType="video/m4v"/>
<mimeMap fileExtension=".3gp" mimeType="video/3gpp"/>
</staticContent>

Answer 2

Could not load type "PresentationLayer.Global"
Check if you namespace is PresentationLayer or is changed? If changed update it in the markup, by right clicking on Global.asax and select "View Markup"