I've been upgraded at work to a Windows 10 machine, from Windows 7. Apparently, this has caused problems.
First, eshell doesn't seem to be able to launch windows processes anymore. I get "Spawning child process: Exec format error". Googling around doesn't seem to give me anything useful.
Second, when I compile, I launch an external command into a build system, which actually runs a batch file in the end. For some annoying reason, this is opening a cmd window with the output, instead of it being captured in emacs' compile buffer (all I get in the compile buffer is the command being issued, and then the error code). That means I don't get a chance to parse the output and see what broke.
I've tried running with no init file, but the same behaviour persists, so at the very least, my .emacs is not interfering, but it's certainly not making things better.
Edit: Interesting note--some executables can't be run by cygwin in windows 10. They don't have a usable set of permissions, and even after I "chmod 777", bash claims that permission is denied when I try to run them. Related? Not sure.
I've included a chunk of my .emacs that might be pertinent.
(setenv "SHELL" "d:/Utilities/cygwin-64/bin/bash.exe")
(setenv "PATH" "d:/Utilities/cygwin-64/bin;d:/Utilities/gnuwin/bin;~/bin;d:/Utilities/emacs-24.5/bin;d:/Utilities/Everything;c:/Windows/System32;c:/ubiperl/script;c:/Perl/bin;d:/Utilities/gnuGlobal/bin;d:/Utilities/sift")
(setenv "MANPATH" "d:/Utilities/cygwin-64/usr/man/")
(setenv "GTAGSFORCECPP" "")
(setq exec-path (append exec-path '("d:/Utilities/cygwin-64/bin")))
(setq exec-path (append exec-path '("d:/Utilities/Everything")))
(setq exec-path (append exec-path '("d:/Utilities/gnuwin/bin")))
(setq exec-path (append exec-path '("d:/Utilities/gnuGlobal/bin")))
(setq exec-path (append exec-path '("d:/Utilities/emacs-24.5/bin")))
(setq exec-path (append exec-path '("d:/Utilities/sift")))
(setq project-grep-path '("e:/assassin/ace/dev/source/scimitar") )
(setq using-unix-filesystems t)
(setq shell-file-name "cmdproxy")
(setq explicit-shell-file-name "bash.exe")
(setq shell-command-switch "/C")
(setq archive-zip-use-pkzip nil)
;;(setq w32-quote-process-args ?\")
(setq w32-enable-italics t)
(setq comint-process-echoes nil)
d:/Utilities/cygwin-64/bin/bash.exe
manually, do you still get the same error? (I mean outside of Emacs)