Dear MeTHoDx
I have this problem now, for several time I try to install devtoolset but I face this error:

warning: rpmts_HdrFromFdno: Header V3 DSA/SHA1 Signature, key ID 1d1e034b: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-cern
GPG key retrieval failed: [Errno 14] Could not open/read file:///etc/pki/rpm-gpg/RPM-GPG-KEY-cern

did you solve this problem? how did you do that?
it's so important to me to solve this problem, please do me a  favour and share your experiment with me
Thanks in advance