As an observation: I only encountered this issue with every Xcode 13 beta, except the first one on my Macbook Pro. The Xcode 13 RC fixed this issue on my MBP.

However, for my mac mini, no version of Xcode 13 is working for me.

Very weird, thank you for the report!

@swift-ci create

I updated my Mac mini to 11.6 to see if Xcode 13 RC 1 would work with that version, and I'm getting the same issue.

Interestingly, when trying to resolve dependencies for RediStack, only a single error is reported by SwiftPM for the SwiftServiceDiscovery package:

https://github.com/apple/swift-service-discovery: error: Failed to clone repository https://github.com/apple/swift-service-discovery:
    Cloning into '/Users/nathanharris/dev/mordil/RediStack/.build/checkouts/swift-service-discovery'...
    fatal: invalid branch name: init.defaultBranch = 

However, when trying to resolve Vapor/Redis, practically the entire dependency graph throws the same error

Cannot repro this, could you please try deleting your SwiftPM cache? It is located at `~/Library/Caches/org.swift.swiftpm`.

@neonichu Does Xcode not do this when using File > Swift Packages > Reset Package Caches?

> Does Xcode not do this when using File > Swift Packages > Reset Package Caches?
@Mordil No, it seems only clean the derivedData related cache.

I can't reproduce it with the latest Xcode both from Xcode or SPM.

Swift version: Apple Swift version 5.5.1 (swiftlang-1300.0.31.4 clang-1300.0.29.6)
Target: arm64-apple-macosx12.0
Unix version: Darwin 21.2.0 Darwin Kernel Version 21.2.0: Tue Nov 16 23:24:18 PST 2021; root:xnu-8019.61.4~4/RELEASE_ARM64_T8101 arm64 arm;
macOS version: 12.1
Xcode-select path: '/Applications/Xcode.app/Contents/Developer'
Xcode: Xcode 13.1 (Build version 13A1030d)

Deleting the cache seems to resolve this. This is why newly cloned projects don't reproduce this