Workaround. Open "<UNITY_INSTALL_DIR>\Editor\Data\il2cpp\libil2cpp\os\Win32\File.cpp" and apply this diff:

diff --git a/libil2cpp/os/Win32/File.cpp b/libil2cpp/os/Win32/File.cpp
index 3d7f48279..1b928f663 100644
--- a/libil2cpp/os/Win32/File.cpp
+++ b/libil2cpp/os/Win32/File.cpp
@@ -503,7 +503,11 @@ namespace os
{
success = TRUE;
// The async write succeeded. Now get the number of bytes written.
+#if IL2CPP_TARGET_WINDOWS_DESKTOP
+ if (GetOverlappedResult((HANDLE)handle, &overlapped, (LPDWORD)&written, TRUE) == 0)
+#else
if (GetOverlappedResultEx((HANDLE)handle, &overlapped, (LPDWORD)&written, INFINITE, FALSE) == 0)
+#endif
{
// Oops, we could not get the number of bytes writen, so return an error.
*error = GetLastError();

See https://forum.unity.com/threads/2019-1-8f1-failed-to-load-il2cpp-unity-on-windows-7-machines.701273/ for more information.

Reproduced in 2019.3.0a8, 2019.2.0b8, 2019.1.8f1 and 2018.4.3f1.
Not reproducible in 2019.3.0a7, 2019.2.0b7, 2019.1.7f1 and 2018.4.2f1.