General setup: So I suppose you’re following https://dev.px4.io/master/en/setup/dev_env_windows_cygwin.html and want to install the Cygwin toolchain. So you downloaded the latest msi installer package (version 0.5). The installer’s filesize is 495MB. You are in the process of the installer itself when you get the message right?
I cannot browse to choose where to install the toolchain. Also the size of the file is way smaller than what I saw in “Installation Instructions”
That sounds like you have a broken/corrupt installer and it fails at that point because in fact nothing really works when the file is corrupt.
downloaded on Git
I’m guessing you downloaded from GitHub. Since I have the suspicion your installer file download is corrupt please try downloading it from S3 (it’s exactly the same file). Open the instructions I linked above and search for “S3”.
Additional info: There’s a script that gets ran all the way at the end of the installer in a console window to restore the symbolic links out of a tar archive within the installed Cygwin environment because the files otherwise get amended by the setup and don’t work anymore. So this would fit your error message about symbolic links.
Developer info: If everything else works but only the symbolic links don’t (which I currently don’t think is the case) here are some pointers about how it all works: