What does “Cannot evaluate expression because the code of the current method is optimized.” mean?

Question

I wrote some code with a lot of recursion, that takes quite a bit of time to complete. Whenever I \"pause\" the run to look at what\'s going on I get:

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Answer 1

In my case I had 2 projects in my solution and was running a project that was not the startup project. When I changed it to startup project the debugging started to work again.

Hope it helps someone.

Answer 2

Look for a function call with many params and try decreasing the number until debugging returns.

Answer 3

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

Answer 4

You are probably trying to debug your app in release mode instead of debug mode, or you have optimizations turned on in your compile settings.

When the code is compiled with optimizations, certain variables are thrown away once they are no longer used in the function, which is why you are getting that message. In debug mode with optimizations disabled, you shouldn't get that error.

Answer 5

The Debugger uses FuncEval to allow you to "look at" variables. FuncEval requires threads to be stopped in managed code at a GarbageCollector safe point. Manually "pausing" the run in the IDE causes all threads to stop as soon as possible. Your highly recursive code will tend to stop at an unsafe point. Hence, the debugger is unable to evaluate expressions.

Pressing F10 will move to the next Funceval Safe point and will enable function evaluation.

For further information review the rules of FuncEval.

Answer 6

Make sure you do not have something like that

[assembly: Debuggable(DebuggableAttribute.DebuggingModes.IgnoreSymbolStoreSequencePoints)]

in your AssemblyInfo