.NET Framework 4.6 AND vs2015 Targeting Errors

Hi,

Did any of you work on upgrading your proj/apps to .NET framework 4.6/VS2015? If yes, what were the issues/errors you faced, and was there a resolution for it? Any pdf files or documents that you may think would help me understanding this .NET framework upgrading issue? Please provide me your real time experience. I would really appreciate your help  Thanks in advance...