Visual upgrade 2010 -> 2013 fails :(

Question

When I follow the wizard steps and do visual experience upgrade of my SharePoint 2010 Solution, which is installed in SharePoint 2013, it ends with the followin error:

Unfortunately we found some problems You'll need to fix these before upgrading. We recommend trying out the fixes on a copy of your site collection before you make changes to your production site.

You need to fix the following problem(s) before upgrading: Missing Site Templates

The following sites are using templates that are not yet supported after upgrade: •http://abc/sites/xyz - EMSMAINSITE#0 Sites that rely on these templates cannot be upgraded at this time, preventing upgrade of this site collection.

I go to my 14\TEMPLATE\1033\XML folder, copy and paste the missing template file EMSMAINSITE#0 to 15\TEMPLATE\1033\XML

Then SharePoint is able to perform the experience upgrade completelly:

Upgrade Status
Upgrade Completed Successfully • Status: Upgrade Completed Successfully • Errors: 0 • Warnings: 0 Letsee the new style

Unfortunately some of the custom ascx controls are missing. For example I don't see my topnavibar on the sitecollection start page, which is the entry point for my sharepoint solution. This ascx control is registered in the .master file:

<%@ Register TagPrefix="mycontrol" TagName="TopNavi" src="~/_controltemplates/TopNavi.ascx" %>

I can see that my old default .master file isn't the current default .master anymore, but seattle.master is the current master page. And in seattle.master, there isn't such registratin like

<%@ Register TagPrefix="mycontrol" TagName="TopNavi" src="~/_controltemplates/15/TopNavi.ascx" %>

When I register my ascx topnavi control in seattle.master and, then something goes wrong and SharePoint says:

Sorry, something went wrong Literal content ('&nbsp ') is not allowed within a 'System.Web.UI.UpdatePanelTriggerCollection'.

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I would like to understand why the visual upgrade fails and what is actually happening when i click to "Start Visual Upgrade" and I would like to correct all this, so that my sitecollection with my all custom ascx controls can be used in SharePoint 2013 look.

Edit: The content of the WEBTEMP.EMSMainSite is:

<?xml version="1.0" encoding="utf-8"?>
<Templates xmlns:ows="Microsoft SharePoint">
  <Template Name="EMSMainSite" ID="16000">
    <Configuration ID="0"
                   Title="EMS"
                   Hidden="FALSE"
                   ImageUrl="/_layouts/images/stsprev.gif"
                   Description="Site template for creating EMS main Site"
                   DisplayCategory="EMS">
    </Configuration>
  </Template>
</Templates>

Answer 1

If you have custom controls or site templates installed, you have to take care by yourself for getting them to Support SP2013 (eg being available in the _controltemplates/15 Folder). MS can only deliver updated controls and templates which they delivered in original SharePoint.

Maybe I´m wrong, but i did met a template called "EMSMAINSITE" so far. Maybe you installed a custom solution which installed that template?