Update . NET Framework for a version larger than 4.0

Question

I opened a request for the IT area to update my website to version 4.5 or higher of . NET Framework.

They said the server has version 4.5 already, the problem is that my site keeps returning the following, at the bottom of the error page:

Version Information: Microsoft . NET Framework Version:4.0.30319; ASP.NET Version:4.7.2053.0

How do I change the version of . NET Framework on my website? You can configure it from the web.Config to use version 4.5 or later?

The impression I have is that they do not know what they are doing and think that the installation on the server ensures that the site is using the version requested by me.

My Web.Config is like this;

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.web>
        <customErrors mode="Off"/>
        <compilation debug="true" targetFramework="4.5" />
        <httpRuntime targetFramework="4.5" />
    </system.web>
    <system.webServer>
        <defaultDocument>
            <files>
                <clear />
                <add value="index.html" />
                <add value="index.php" />
                <add value="Default.htm" />
                <add value="Default.asp" />
                <add value="index.htm" />
                <add value="iisstart.htm" />
                <add value="Default.aspx" />
            </files>
        </defaultDocument>
    </system.webServer>
</configuration>

That hasn’t solved anything yet.

Still sent an image that I can not upload here, so I will try to write (no header):

+-------------+-----------+----------+--------------+-----------------------+-----+
|  .NET v4.5  |  Started  |   v4.0   |  Integrated  |  ApplicationPollD...  |  0  |
+-------------+-----------+----------+--------------+-----------------------+-----+