Windows 10 did auto-update (Cumulative Update for Windows 10 for 
x64-based Systems (KB3093266)) yesterday. My sys auto rebooted this 
morning.

Now, when I try to launch "Cygwin Terminal" from the windows desktop I get:

/usr/bin/mintty:  could not detach from caller.  Try '-help' for more 
information.

The actual runstring for the shortcut is:

C:\cygwin\bin\mintty.exe -i /Cygwin-Terminal.ico -

Running mintty --version reports:  mintty 2.1.5 (i686-pc-cygwin)

I can launch bash from windows cmd shell:

/usr/bin/bash

and I get a bash command prompt.  If I try to execute anything (from 
inside that bash shell), for example, ls, I get:

Terry@PaceBend /cygdrive/c/Users/Terry/Desktop
$ ls
       2 [main] bash (4820) C:\cygwin\bin\bash.exe: *** fatal error - 
cygheap base mismatch detected - 0xF4B400/0xDFB400.
This problem is probably due to using incompatible versions of the 
cygwin DLL.
Search for cygwin1.dll using the Windows Start->Find/Search facility
and delete all but the most recent version.  The most recent version 
*should*
reside in x:\cygwin\bin, where 'x' is the drive on which you have
installed the cygwin distribution.  Rebooting is also suggested if you
are unable to find another cygwin DLL.
       1 [main] bash 5244 fork: child -1 - forked process 4820 died 
unexpectedly, retry 0, exit code 0xC0000142, errno 11
bash: fork: retry: No child processes
       3 [main] bash (6124) C:\cygwin\bin\bash.exe: *** fatal error - 
cygheap base mismatch detected - 0xF4B400/0x10AB400.
This problem is probably due to using incompatible versions of the 
cygwin DLL.
Search for cygwin1.dll using the Windows Start->Find/Search facility
and delete all but the most recent version.  The most recent version 
*should*
reside in x:\cygwin\bin, where 'x' is the drive on which you have
installed the cygwin distribution.  Rebooting is also suggested if you
are unable to find another cygwin DLL.
1022635 [main] bash 5244 fork: child -1 - forked process 6124 died 
unexpectedly, retry 0, exit code 0xC0000142, errno 11
bash: fork: retry: No child processes
       2 [main] bash (2932) C:\cygwin\bin\bash.exe: *** fatal error - 
cygheap base mismatch detected - 0xF4B400/0xDCB400.
This problem is probably due to using incompatible versions of the 
cygwin DLL.
Search for cygwin1.dll using the Windows Start->Find/Search facility
and delete all but the most recent version.  The most recent version 
*should*
reside in x:\cygwin\bin, where 'x' is the drive on which you have
installed the cygwin distribution.  Rebooting is also suggested if you
are unable to find another cygwin DLL.
3059295 [main] bash 5244 fork: child -1 - forked process 2932 died 
unexpectedly, retry 0, exit code 0xC0000142, errno 11
bash: fork: retry: No child processes
       3 [main] bash (5540) C:\cygwin\bin\bash.exe: *** fatal error - 
cygheap base mismatch detected - 0xF4B400/0xD8B400.
This problem is probably due to using incompatible versions of the 
cygwin DLL.
Search for cygwin1.dll using the Windows Start->Find/Search facility
and delete all but the most recent version.  The most recent version 
*should*
reside in x:\cygwin\bin, where 'x' is the drive on which you have
installed the cygwin distribution.  Rebooting is also suggested if you
are unable to find another cygwin DLL.
7087580 [main] bash 5244 fork: child -1 - forked process 5540 died 
unexpectedly, retry 0, exit code 0xC0000142, errno 11
bash: fork: retry: No child processes
       3 [main] bash (2896) C:\cygwin\bin\bash.exe: *** fatal error - 
cygheap base mismatch detected - 0xF4B400/0x106B400.
This problem is probably due to using incompatible versions of the 
cygwin DLL.
Search for cygwin1.dll using the Windows Start->Find/Search facility
and delete all but the most recent version.  The most recent version 
*should*
reside in x:\cygwin\bin, where 'x' is the drive on which you have
installed the cygwin distribution.  Rebooting is also suggested if you
are unable to find another cygwin DLL.
15118128 [main] bash 5244 fork: child -1 - forked process 2896 died 
unexpectedly, retry 0, exit code 0xC0000142, errno 11
bash: fork: Resource temporarily unavailable

Terry@PaceBend /cygdrive/c/Users/Terry/Desktop
$

I checked the cygwin1.dll and it is in the proper place and is dated the 
same as the day I updated cygwin for windows 10.

cygcheck file attached.

I hope this is the correct list for this issue.  I spent a long time 
trying to search for a solution and/or if it had already been reported 
somewhere, but I didn't find it.  Sorry if I duplicated the reporting or 
it is in the wrong email list.

Terry