Swift Package Manager "failed to resolve dependencies" in CI

Swift Package Manager could not compute a set of package versions that satisfies your dependencies. Either a package URL is unreachable, Package.resolved is stale, or two requirements are incompatible.

What this error means

A build or xcodebuild -resolvePackageDependencies fails with "failed to resolve dependencies" - sometimes naming a package it could not fetch, sometimes a version conflict. Network causes pass on retry; conflicts and stale pins fail every time.

xcodebuild output

error: failed to resolve dependencies:
Dependencies could not be resolved because root depends on 'swift-log' 1.5.0..<2.0.0
and 'metrics' depends on 'swift-log' 1.0.0..<1.5.0.

Common causes

Stale or conflicting Package.resolved

A Package.resolved that no longer matches Package.swift, or two packages requiring non-overlapping versions of a shared dependency, leaves SPM with no solvable set.

Unreachable package URL

A transient network failure or an auth issue cloning a Git package URL (a private repo without credentials) makes resolution fail to fetch the package.

How to fix it

Re-resolve and update the pins

Refresh the resolved file so it matches the manifest, then resolve.

Terminal

xcodebuild -resolvePackageDependencies -workspace App.xcworkspace -scheme App
# or update pins when a constraint changed:
swift package update

Cache SPM and provide credentials for private packages

Cache the resolved packages and ensure private Git URLs can authenticate.

.github/workflows/ci.yml

- uses: actions/cache@v4
  with:
    path: ~/Library/Developer/Xcode/DerivedData/**/SourcePackages
    key: spm-${{ hashFiles('**/Package.resolved') }}

Resolve a version conflict

Read which two requirements conflict in the error.
Loosen your own version range so it overlaps the dependency’s.
Upgrade the lagging package to a release that accepts the newer shared dependency.

How to prevent it

Commit Package.resolved so CI resolves to the same versions.
Cache the SPM SourcePackages directory keyed on Package.resolved.
Provide credentials for any private Git package URLs in CI.