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  Cannot evaluate expression because the code of the current method is optimized    Even a line like  int i   -3  doing a quick watch on i  I get  Cannot obtain value of local or argument  i  as it is not available at this instruction pointer  possibly because it has been optimized away    This link referenced in a similar question doesn t seem to apply   Is there a setting I am missing

User · Answer

One other thing that you may do is  create a file with the same name as the dll that is optimized but with ini extension and add the following to it     NET Framework Debugging Control  GenerateTrackingInfo 1 AllowOptimize 0  This will tell the JIT not to optimize your variables   Note that you still need the pdb  so you will end up with something like this  yourDll dll yourDll pdb yourDll ini  This works specially well in scenarios when you don t have access to re-generate the dlls with debug option   http   www hanselman com blog DebugVsReleaseTheBestOfBothWorlds aspx

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When you see the  Cannot evaluate expression because the code of the current method is optimized   message after issuing a Debugger Break   statement then please make sure you press F10 to step to the next statement   Once stepped to the next statement  and assuming you are running a Debug build  this message should disappear

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I had the same problem  But in my case  the Debuggable attribute was hard coded in the AssemblyInfo cs file of my project and therefor not  over- written by compilation  It worked after removing the line specifying the Debuggable attribute

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I had the same problem in VS2008  In my case it was solved via solution-rebuild

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If you re trying to debug an ASP NET project  ensure that the project s Properties   Web   Servers dropdown is set to  IIS Express   in addition to checking everything else here

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In VS2013 go to  Tools -  Options -  Debugging -  General and enable  Use managed compatibility mode   This disables the new function evaluation behavior

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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

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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

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I had this issue when I was using VS 2010  My solution configuration has  Debug  selected  I resolved this by unchecking the Optimize Code property under project properties  Project  right Click    Properties    Build  tab     uncheck Optimize code

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I started receiving this message when I migrated to Visual Studio 2017   None of the ideas on this page that I tried worked for me   On another post I found this suggestion and it DID work - remove    assembly  Debuggable DebuggableAttribute DebuggingModes IgnoreSymbolStoreSequencePoints        from your AssemblyInfo file

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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

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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

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I had this problem with an F  project that had been here and there between Visual Studio and MonoDevelop  perhaps originating in the latter  I forget   In VS  the optimize box was unchecked  yet optimization certainly seemed to be occuring as far as the debugger was concerned    After comparing the XML of the project file against that of a healthy one  the problem was obvious  the healthy project had an explicit  lt optimize gt false lt  optimize gt  line  whereas the bad one was missing it completely  VS was obviously inferring from its absence that optimization was disabled  while the compiler was doing the opposite   The solution was to add this property to the project file  and reload

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Try to run in debug mode If you are running in release mode you will get this message

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I had the same issue in VS 2010  Cleaned-up and rebuild the solution and it worked

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I had the same problem while debugging a class library from a testbed web app  I was referencing the release version in the testbed and that was set to be optimised in the class library properties   Un-ticking the optimise code checkbox for the release version in the class library properties  just while I am writing it  has solved the issue

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

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Apart from  Kragen mentioned  If you are debugging a web project  close the visual studio and try deleting the temporary files at C  Windows Microsoft NET Framework v2 0 50727 Temporary ASP NET Files

User · Answer

It sounds like you are debugging an optimised   release build  despite having the optimised box un-checked   Things you can try are    Do a complete rebuild of your solution file  right click on the solution and select Rebuild all  While debugging open up the modules window  Debug -  Windows -  Modules  and find your assembly in the list of loaded modules   Check that the Path listed against your loaded assembly is what you expect it to be  and that the modified timestamp of the file indicates that the assembly was actually rebuilt  The modules window should also tell you whether or not the loaded module is optimised or not - make sure that the modules window indicates that it is not optimised    If you cant t see the Modules menu item in the Debug -  Windows menu then you may need to add it in the  Customise     menu

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

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In Visual Studio 2012 enabling the  Managed  option from Tools   Debugging   Just-In-Time worked for me

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I had mixed c   cli mfc extension dlls  that were optimised even if debug configuration  seen from VS 2017 Modules window    As previous answer suggested I changed  In VS2013 go to  Tools -  Options -  Debugging -  General and enable  Use managed compatibility mode   This disables the new function evaluation behavior   That settings find also in VS 2017   But that was not enough  so I also copied the UseDebugLibraries setting from another MFC app s project file to extension dll project file        lt PropertyGroup Condition     Configuration    Platform     Debug Win32   Label  Configuration  gt                   lt UseDebugLibraries gt true lt  UseDebugLibraries gt    Then rebuild and that fixed the problem

[c#] "Cannot evaluate expression because the code of the current method is optimized" in Visual Studio 2010

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