Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires silverstripe/silverstripe-omnipay dev-master, found silverstripe/silverstripe-omnipay[dev-main, 1.0.0-beta1, ..., 1.x-dev, 2.0-alpha, ..., 2.x-dev, 3.0.0-alpha1, ..., 3.x-dev, 4.x-dev (alias of dev-main)] but it does not match the constraint. Perhaps dev-master was renamed to dev-main?