fork issue when lauching cygwin64 process from 32bit native app on Windows 10 TH2

Corinna Vinschen
Thu Dec 3 22:52:00 GMT 2015

On Dec  1 19:27, nu774 wrote:
> After upgrading to Windows 10 TH2 (ver 1511, build 10586), any attempt
> to launch a cygwin64 process from 32bit native app (for example,
> C:\windows\syswow64\cmd.exe) *always* results in a fork error.
> To be precise, I can execute 64bit bash.exe from 32bit cmd.exe.
> However, this bash process never succeeds in forking a child (ls or
> something).
> Also, I cannot launch 64bit mintty.exe from 32bit cmd.exe. It always
> fails in a error dialog saying that:
> mintty: could not detach from caller
> Try '--help' for more information.
> When launching from 64bit app, this issue doesn't happen.

I created a workaround for this issue and uploaded new developer
snapshots to, as well as a new Cygwin
test release 2.4.0-0.7 with this change

Please give any of them a try.


Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat
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