“Cannot evaluate expression because the code of the current method is optimized” in Visual Studio 2010

Question

I am using Visual Studio 2010 in debug mode and I have \"optimize code\" unchecked. I can\'t quick watch (or hover on) any variable in the debugger. I get this error \"Canno

Answer 1

While the project was in debug mode, the solution was not. When I changed it, it worked.

Answer 2

I realize this is a later answer, but I found another reference to a way to address this issue that might help others in the future. This web page describes setting an environment variable (COMPLUS_ZapDisable=1) that prevents optimization, at least it did for me! (Don't forget the second part of disabling the Visual Studio hosting process.) In my case, this might have been even more relevant because I was debugging an external DLL thru a symbol server, but I'm not sure.

Answer 3

My situation was not covered by any of the above answers. I found the following: MSDN article on threading that explains that when stuck in some primitive native threading operations, the debugger can't access the data. As an example, when a thread is sitting on Task.Wait(), this comes up.

Answer 4

vickramds's comment above, referring to http://torulflundgren.blogspot.com.au/2010/03/cannot-obtain-value-of-local-or.html , did it for me. I checked everything - deleted all the dll, pdb files from local bin folders, Clean, Rebuild, cleared all folders of Temporary ASP.NET Files, ensured TRACE/DEBUG flags were set, checked the DLL paths, etc.

To put it down so it isn't lost, for the affected project(s):

Project Properties --> Build --> Advanced --> Debug Info: Full.

You want to check that you have the Debug configuration selected before you do this, unless of course, you intended otherwise.

Answer 5

For me it was happening in VS2017 and VS2019. It stopped happening after I selected the option "Suppressed JIT optimization on module load".

Answer 6

Regarding the problem with "Optimize code" property being UNCHECKED yet the code still compiling as optimized: What finally helped me after trying everything was checking the "Enable unmanaged code debugging" checkbox on the same settings page (Project properties - Debug). It doesn't directly relate to the code optimization, but with this enabled, VS no longer optimizes my library and I can debug.