While debugging VS2012 I have found that I can no longer access variable values:
Please check the answer here.
In a nutshell, you need to open: Tools > Options > Debugger > General, and enable the flag [Use Managed Compatibility Mode] at the end of the list.
That happens sometime when your Optimize Code box is ticked in project properties under Build section.
I've eventually managed to sort this out by myself - so I'll give my solution here in case anyone else has the same problem:
I found that in Tools->Options->Debugging->Symbols was pointing to an old NuGet symbol server. Somehow a wrong symbol server looked like it was taking down the entire Locals and Immediate Window systems.
Updating the symbol server fixed my problems.
I had the same problem with Visual Studio 2013 Update 5 on Windows 10 while using remote debugging.
According to another SO question the locals/variables are broken in the remote debugging tools.
I haven't found a solution yet, but I'm going to switch to Visual Studio 2015 so I haven't really been looking for it either...
I will add this answer as I had the same problem with a different resolution.
I had mistakenly closed the locals window and could not find it as it was not with other windows under the VIEW menu. I found it under the DEBUG menu Windows option.
or Optionally:
Ctrl+Alt+V, L
I will add this answer as I had the same problem with a different resolution.
I got this too in a Web project. Neither restarting Visual Studio or any other solution in this thread sovled it.
My solution was to restart IIS. After that I rebuilt the project and started it and got locals to work again.