Everytime I build a unreal engine project, vs keeps warning like this: unable to get MBCS string

Question

2>    --------------------Project: Default-------------------------------------------
2>    MyProjectCharacter.cpp (0:01.59 at +0:00)
2>    EXEC : warning : unable to get MBCS string (input text '??: ?? ??:%s%s
2>    ', library C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.26.28801\bin\HostX64\x64\1042\clui.dll)
2>    UE4Editor-MyProject-0002.dll (0:00.68 at +0:01)
2>       Creating library C:\Users\grand\GameDev\MyProject\Intermediate\Build\Win64\UE4Editor\Development\MyProject\UE4Editor-MyProject-0002.suppressed.lib and object C:\Users\grand\GameDev\MyProject\Intermediate\Build\Win64\UE4Editor\Development\MyProject\UE4Editor-MyProject-0002.suppressed.exp
2>    UE4Editor-MyProject-0002.lib (0:00.07 at +0:02)
2>       Creating library C:\Users\grand\GameDev\MyProject\Intermediate\Build\Win64\UE4Editor\Development\MyProject\UE4Editor-MyProject-0002.lib and object C:\Users\grand\GameDev\MyProject\Intermediate\Build\Win64\UE4Editor\Development\MyProject\UE4Editor-MyProject-0002.exp
2>    MyProjectEditor.target (0:00.17 at +0:02)
2>    ---------------------- Done ----------------------

There's no problem with compiling, but this warning keeps showing up on the output window. Is this just a trivial thing that has nothing to do with the game I'm making? or can it make some problems later? I googled this warning, but nothing I can find. What I did to solve it is downgrading engine version to 4.24, reinstalling VS and UE4, installing MSVC v141, v140(verion 2017, 2015).

Answer 1

This is sample from UE4 Internal String Representation

UE4 Internal String Representation : All strings in Unreal Engine 4 (UE4) are stored in memory in UTF-16 format as FStrings or TCHAR arrays. Most code assumes 2 bytes is one codepoint so only the Basic Multilingual Plane (BMP) is supported so Unreal's internal encoding is more correctly described as UCS-2. Strings are stored in the endian-ness appropriate for the current platform. When serializing to packages to/from disk or during networking, strings with all TCHAR characters less than 0xff are stored as a series of 8-bit bytes, and otherwise as 2-byte UTF-16 strings. The serialization code can deal with any endian conversion as necessary. When Unreal loads an external text file (for example reading a .INT file at runtime) it is almost always done with the appLoadFileToString() function found in UnMisc.cpp. The main work occurs in the appBufferToString() function. This function recognizes the Unicode byte-order-mark (BOM) in a UTF-16 file and if present, will load the file as UTF-16 in either endian-ness. What happens when the BOM is not present depends on the platform. On Windows, it will attempt to convert the text to UTF-16 using the default Windows MBCS encoding (eg Windows-1252 for US English and Western Europe, CP949 for Korean and CP932 for Japanese) and uses MultiByteToWideChar(CP_ACP, MB_ERR_INVALID_CHARS...). This was added around the July 2009 QA build. If this conversion fails on platforms other than Windows, it will just read each byte and pad it to 16-bits to make an array of TCHARs. Note that there is no code to detect or decode UTF-8 encoded text files loaded with appLoadFileToString().

It seems your program faces a language unicode warning conversion. If your read or converted string is correct with your language settings, then you can ignore this Warning. But try some conversion with all your language characters to checks if all are well converted. Otherwise, your can force language conversion using :

string utf8String = Encoding.UTF8.GetString(Encoding.ASCII.GetBytes(text));

Take also a look at this SO question : How to convert Unicode string to a TCHAR system with Unreal project

Answer 2

Wow it was because of IncreBuild. I deleted it, and the warning doesn't come out anymore.