How to fix Error LNK2001 unresolved external symbol _mainWCRTStartup?

Question

How to fix Error LNK2001 unresolved external symbol _mainWCRTStartup?

Ng SG 21

Hello,

I'm migrating an old project to VS2019. The project originally is created with VS2005.

The migration start with creating a new empty main function as shown:

int _tmain(int argc, TCHAR* argv[], TCHAR* envp[])
{
return 0;
}

As I want to run the project with UNICODE , I set the entry point of the project to mainWCRTStartup. I try to compile but failed with error:

1) LNK 2001 unresolved external symbol _mainWCRTStartup
2) LNK 2019 unresolved external symbol __except_handler4_common referenced in function __except_handler4

How can I fix this problem?

Geng

cheong00 3,486 Reputation points Volunteer Moderator

2021-02-19T01:37:38.28+00:00

I saw report that this contains sensitive information but I fail to find one.

If you mean the build path, the user also sign every message with the exact same name.

Other parts of this threads are just pretty common C++ things.

Accepted answer

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cheong00 3,486 Reputation points Volunteer Moderator

2021-02-19T01:37:38.28+00:00

I saw report that this contains sensitive information but I fail to find one.

If you mean the build path, the user also sign every message with the exact same name.

Other parts of this threads are just pretty common C++ things.

Answer 1

RLWA32 49,636

Remove your setting of the entry point to mainWCRTStartup. This is the wrong name. For a well formed C++ Console application project you can leave that project property blank. The linker will use the correct symbols.

If you want to set the entry point then it should be wmainCRTStartup for a UNICODE build

Ng SG 21 Reputation points

2020-08-30T03:12:15.793+00:00
Hello RLWA32-6355,

I try both:

Without setting the entry point and

With the entry point set to wmainCRTStartup.

I'm facing the below error.

Error LNK2019 unresolved external symbol _main referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ)

How to solve this?

Thank You.

Geng
WayneAKing 4,931 Reputation points

2020-08-30T04:28:52.557+00:00
The fact that the current error names "main" rather than wmain
suggests that you are not building for Unicode. Are you sure the
project properties are set to use the Unicode character set?

Did you also try it with the "Entry Point" property left clear?

Wayne
RLWA32 49,636 Reputation points

2020-08-30T10:44:32.23+00:00

You should also verify that you are setting project properties for the configuration(Debug/Relase) and platform(32-bit/64-bit) that you are actually building. So if you are doing a Debug build but set the properties for the Release configuration your changes will not be used during the build. Same thing if you use the wrong configuration.

When changing project properties try selecting All Configurations and All platforms before making the change.
Ng SG 21 Reputation points

2020-09-02T02:52:38.417+00:00

Hello All,

I rebuilt the project based on your advices.
Below is the result and the settings.

Result:
Error LNK2019 unresolved external symbol _wmain referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ) TestProject C:\Users\geng\source\repos\TestProject\MSVCRTD.lib(exe_wmain.obj) 1

Settings:
Character set: Use Unicode Character Set (Thanks WayneAKing-0228 for the correction)
Preprocessor Definition: _UNICODE;UNICODE
SubSystem: Console(/SUBSYSTEM:CONSOLE)
Entry Point: wmainCRTStartup or left blank
project properties for the configuration: Debug (x86/Win32)

I try to change _tmain to wmain and the build success. I would like to maintain it as _tmain so it can switch between the Unicode and Multi-Byte character set.

Thank You.

Best regards,
Geng
RLWA32 49,636 Reputation points

2020-09-02T03:08:29.323+00:00
Did you remember to use

#include <tchar.h>
Ng SG 21 Reputation points

2020-09-02T04:45:10.113+00:00

Thank You RLWA32-6355. Finally the build pass.

Based on the previous project (VS2005), <tchar.h> was included in <windows.h>.
Seem like I will need to include <tchar.h>during migrating the project to VS2019.

Thanks a lot!

Regards,
Geng

Answer 2

Dylan Zhu-MSFT 6,426

Hi Geng,

You could try to set the Entry Point to "mainCRTStartup ", which also works for console application.

If it doesn't work, please confirm if the subsystem is "Console" in Project properties-> Linker -> System -> SubSystem.

Best Regards,
Dylan

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How to fix Error LNK2001 unresolved external symbol _mainWCRTStartup?

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