Downloading failed: The GPG keys listed for the "Fedora 21 - x86_64" repository are already installed but they are not correct for this package.
Check that the correct key URLs are configured for this repository.
Failing package is: libpurple-2.12.0-2.fc26.x86_64
GPG Keys are configured as: file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-21-x86_64