SSRS report files (.rdl) how to upgrade to latest?

I have been using Visual Studio 2010 for Reporting Services projects, with a SQL server 2012 reporting services back-end. To display the report we went from version 10,to 11 with the Reporting viewer in asp.net like so with no problems.

<%@ Register Assembly="Microsoft.ReportViewer.WebForms, Version=13.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91"
Namespace="Microsoft.Reporting.WebForms" TagPrefix="rsweb" %>

 <rsweb:ReportViewer ID="ReportViewer03" runat="server" Font-Names="Verdana" 
                    Font-Size="8pt" Height="400px" ProcessingMode="Remote" Width="950px">
                    <ServerReport ReportPath="/ReportsProgram_YEAR8/Rpt03_SurveyCountsByLanguageMethod" 
                        ReportServerUrl="http://sql2012a/ReportServer_SQL2016" />
                </rsweb:ReportViewer>

Installing SQL Server 2016, and reporting services, and SQL Data Tools 2015 all went well.

i can change the version of the assembly above to 11.0 and the report will still render, fine the old looking way.

But when using Visual Studio 2015 or SQL Data Tools 2015 opening the old project file or individual .rdl files, did not prompt to upgrade like I am seeing on the internet. As far as i remember there was no SQL Data Tools 2013 so I never had a chance to upgrade.

Anyway looking inside the report files, its obvious the xml tag has not been upgraded. Not only that there the report has issues. (see screen shot below)

Now I have created a new report from scratch and the drop down does work for export and print, but the area below the toolbar with the two drop downs is still present with print, cancel and done. I have upgraded my ajaxtoolkit and everything. I have no choice but to continue to use SQL Reporting Services 2012 (very sad)

Can anyone shed any light as to the issues?

You need to be using report viewer 13 for working with SSRS 2016. It is available on nuget as a preview release.

Install-Package Microsoft.ReportingServices.ReportViewerControl.WebForms.Preview

https://blogs.msdn.microsoft.com/sqlrsteamblog/2016/09/23/embed-paginated-reports-into-asp-net-web-apps-using-the-report-viewer-2016-control/

If SQL Server Data Tools or SQL Server Management Studio for SQL 2016 is installed, make sure it’s updated to the latest version. Earlier versions of SSDT incorrectly gac’ed certain dlls which conflict with the Report Viewer Control. You may need to manually delete the V13 dll's from \windows\assembly\gac_msil to permanently remove them.

How to uninstall

gacutil /u "Microsoft.ReportViewer.WebForms, Version=13.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91, processorArchitecture=MSIL" /f

gacutil /u "Microsoft.ReportViewer.WinForms, Version=13.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91, processorArchitecture=MSIL" /f

gacutil /u "Microsoft.ReportViewer.WebDesign, Version=13.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91, processorArchitecture=MSIL" /f

gacutil /u "Microsoft.ReportViewer.Common, Version=13.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91, processorArchitecture=MSIL" /f

If you get Unable to uninstall: assembly is required by one or more applications https://support.microsoft.com/en-us/kb/873195