HTTP Error 500.19 - Internal Server Error

The requested page cannot be accessed because the related configuration data for the page is invalid.

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Mostly this is caused by .NET not being configured correctly for IIS.
Fixes shown here: https://stackoverflow.com/questions/4890245/how-to-add-asp-net-4-0-as-application-pool-on-iis-7-windows-7

In some cases this can also be caused my the fact that you did have the IIS Url Rewriter extension installed in the old server and not (yet) on the new server.
In that case the error is caused by the redirect lines in the web.config file.

Download and install the Url Rewiter Extension and the site should run fine again: https://www.iis.net/downloads/microsoft/url-rewrite