Still receiving error message "Assembly Reference "C:\Developer\GB_Registers \lib\RCAJAX\2017.1.228.45\AdditionalLibraries\Bin45\Telerik.Windows.Documents.Spreadsheet.dll" was not updated properly. This usually happens when an assembly exists both in the GAC and in a local folder. Please, use the GAC reference instead. Using VS 2015. 
If the issue has been resolved what are my next steps?

Just upgraded to VS2015....still googling the Error	:

'Could not load file or assembly 'Telerik.Web.UI, Version=2015.3.1111.45, Culture=neutral, PublicKeyToken=121fae78165ba3d4' or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515)'"

Which is also a long term bug with a new flavor.

Agree with John Friel, fix these low-priority "annoyances" instead of leaving them hanging for years... of to waste more hours of my day figuring out why a project that worked just fine in VS2013 errors out in VS2015.

A 4 year old bug like this and it is "low priority"?  I just wasted 10 minutes only to find out I didn't need to.  Just think of all the people experiencing 10 minutes of googling to find out you really don't care.  

Just saying....

Updated Visual Studio Telerik Extension; still crashes visual studio during the download process of the newest version of Kendo UI MVC. Confirming I also still experiencing the error message when updating. version update 2016.1.113.45

Still happend the message when update to RCAJAX\2016.1.113.45\AdditionalLibraries\Bin45

Still receiving error message "Assembly Reference "C:\Program Files (x86)\Telerik\UI for ASP.NET MVC Q3 2015\wrappers\aspnetmvc\Binaries\Mvc5\Kendo.Mvc.dll" was not updated properly. This usually happens in Visual Studio 2010 when an assembly exists both in the GAC and in a local folder. Please, use the GAC reference instead."

Known issue since 2012, its 10.1.2015, nothing about this upgrade process using the visual studio extension works. The VS extension crashes if you use it to download the updated Kendo UI as well.