I have this problem with a private repo (which I have full access) on github.com too. Things I've tried (with Xcode not running) that did not help: deleting DerivedData deleting org.swift.swiftpm in both Library and Library/Caches deleting Xcode user defaults (com.apple.dt.Xcode) removing github items from Keychain Access restarted Mac after deleting above Each time I try to resolve packages it fails with "SSH Key failed to verify". When I click on "Edit Credentials" it asks for my GitHub Personal Access token. I have an ssh key. It works everywhere except in Xcode - this also worked a month ago from within Xcode. This feels like it broke in Xcode RC2. The only thing that works is to run xcodebuild -resolvePackageDependencies in the terminal in my repo root. Which is a pain when you do a lot of branch switching or merging main into the branch. This is also how I know that the key works fine and I suspect it's a problem with Xcode itself.