PROBLEM:

CYGWIN (open source) installation fails on WINDOWS 10 with exit code 256

SOLUTION:

1. You must install cygwin in a subfolder e.g. "D:\subfolder"

2. add the /bin directory at the beginning of the PATH environment variable (PATH = D:\subfolder\bin)

3. install e.g. BOM in the subfolder "D:\Subfolder\Axway"

In case you will also have a PERL error, please check this article:

https://support.axway.com/kb/179867/language/en