"xxx.exe is not a valid Win32 application" after VS just built it

Question

I have been successfully developing a WinAPI application in visual studio 2015 (using the IDE) on my Windows-7-64 PC. I usually test the program in Release mode. I then made some edits to my source. The program compiled and linked without error but the program did not behave quite as I expected, so I switched to Debug mode and tried to build and run. Again VS compiled and linked without error but then complained "Unable to start program 'f:\dropbox\blah\x64\Debug\xxx.exe'. 'f:\dropbox\blah\x64\Debug\xxx.exe' is not a valid Win32 application". I thought it was strange, so I flipped back to release mode and tried again - the program started fine. I made some edits and re-built a few times, but then later VS declared "Unable to start program 'f:\dropbox\blah\x64\Release\xxx.exe'. 'f:\dropbox\blah\x64\Release\xxx.exe' is not a valid Win32 application". I tried clean all, restarted VS, even restarted my PC.. but all to no avail, I still get exactly the same errors. EDIT: After reading abou…

Accepted Answer

```
  77BB8000 .data
```

That's almost certainly the problem, you have a very large data section. Its size is suspiciously close to what it is possible for a single executable module on Windows. You can get a more consistent repro from this sample C program:

```
unsigned char kaboom[0x7d000000];

int main()
{
    return 0;
}
```

Not a very good error message btw, Microsoft did not reserve an error code for this corner-case. And sure, it is not going to repeat that well when you are close to the edge with 0x77BB8000. The executable image must fit a single view of the memory-mapped file that the loader creates to map the code and data into memory. The view has a hard upper-limit of 2 gigabytes, fundamental for a 32-bit process and an MMF view size restriction even on the 64-bit version of Windows.

The amount of space that is available for that data section varies from one run to the next. Subtracted from the view size are the non-mappable regions at the start and the end of the address space and the space required for the operating system DLLs (at least ntdll.dll and kernel32.dll) in a 32-bit EXE process. And the space you lose due to ASLR (Address Space Layout Randomization), a number that changes. And DLLs that are injected, like those used by anti-malware and Dropbox.

It can't be guessed why your data section needs to be so large. Ask the linker to generate a .map file so you get a breakdown of the section, the large global variable ought to jump out. Be sure to target x64 so you have lots of address space available and use the free store (malloc etc) to allocate large arrays.

"xxx.exe is not a valid Win32 application" after VS just built it

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