This is usually because you are not using Apple's copy of python (e.g. /usr/bin/python) but instead one provided by MacPorts or Homebrew. The non-Apple python ships without any SSL root certificates so you see this error. Try running the installer with: /usr/bin/python fslinstaller.py Duncan On 31 Jul 2017, at 19:11, Dan Levitas <[log in to unmask]<mailto:[log in to unmask]>> wrote: Hello FSL, I'm trying to install fsl 5.0.10 on my terminal, but whenever I try to run the fslintaller.py script I get this error: [FAILED] [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:661) I don't really know much about trouble shooting certificate verification, so I was wondering if someone knew how to best resolve this issue. My Python version: Python 2.7.13 My openssl version: OpenSSL 1.0.2l 25 May 2017 Thanks for the help. Dan -- Duncan Mortimer Senior Informatics Officer, Wellcome Centre for Integrative Neuroimaging, FMRIB, University of Oxford John Radcliffe Hospital, Oxford, UK