The . NET Framework version below 4 does not support mixed-mode debugging of the x64 process. This means that when you are debugging, you cannot step from managed code to native code, and you cannot step from native code to managed code.
Problem solving
Update the project to use the Microsoft. NET Framework version 4 or later.
Or
Debug managed code and native code in a separate debugging session.
Or
Debug the mixed code as a 32-bit process, as described in the following procedure.
Change the platform to 32-bit (Visual Basic or C #)
In Solution Explorer , right-click your project, and then select Properties.
In the property page, click the Compile or debug tab.
Click Platform, and then select x86 from the list of platforms.
By Default, the Visual Basic and C # compilers generate code to run on any CPU by default. on a 64-bit computer, these binaries run as 64-bit processes. to run in a 32-bit process, you must select "Win32" instead of "AnyCPU".
Change the platform to 32-bit (C + +)
In Solution Explorer , right-click the project and click Properties.
In the Properties page, click Platform, and then select Win32 from the list of platforms.
The . NET Framework version below 4 does not support mixed-mode debugging of the x64 process. This means that when you are debugging, you cannot step from managed code to native code, and you cannot step from native code to managed code.
Problem solving
Update the project to use the Microsoft. NET Framework version 4 or later.
Or
Debug managed code and native code in a separate debugging session.
Or
Debug the mixed code as a 32-bit process, as described in the following procedure.
Change the platform to 32-bit (Visual Basic or C #)
In Solution Explorer , right-click your project, and then select Properties.
In the property page, click the Compile or debug tab.
Click Platform, and then select x86 from the list of platforms.
By Default, the Visual Basic and C # compilers generate code to run on any CPU by default. on a 64-bit computer, these binaries run as 64-bit processes. to run in a 32-bit process, you must select "Win32" instead of "AnyCPU".
Change the platform to 32-bit (C + +)
In Solution Explorer , right-click the project and click Properties.
In the Properties page, click Platform, and then select Win32 from the list of platforms.
Mixed-mode debugging of the x64 process is supported only when you are using the Microsoft. NET Framework version 4 or later