Goal: We want to upgrade CI from Xcode 16.4 → 26.0.0. Along with this we are moving all of our snapshot testing over to iOS 26, on an iPhone 17 Pro. I have my branch made with all the changes, but when I run our testing suite on CircleCI, it is never able to finish due to it hanging indefinitely. This issue only occurs on my branch thats set up to migrate over to Xcode 26, and does not happen on our main branch.
I have seen the posts about the iPhone simulator booting issues on Xcode 26, and I have followed instructions here to make sure that it is prebooted.
Env (CI): m4pro.medium · macOS 15.6 · Xcode 26.x (Swift 6.0) · iOS 26.0 simulators · device: iPhone 17 Pro.
What happens:
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Jobs start fine; hundreds of tests run and pass.
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~30 minutes in, the CircleCI console output stops mid-run (not the same test each time, and I have verified that every test it’s “hangs” on will pass when I run it locally).
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The job hangs, and eventually our 20 minute timeout kicks in, and kills the job. This counts as a failure for our required tests, since the suite never finishes.
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Reproducible with and without parallelization (we normally use parallel tests; tried disabling—same behavior).
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We’re pinning Xcode 26 on M4 Pro, per CircleCI guidance
What I’ve already done:
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Preboot simulator via
circleci/macos@2(preboot-simulatoriPhone 17 Pro / iOS 26.0). C -
Tried parallel on/off and reduced workers.
Questions:
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Is there a known iOS-26/Xcode-26 hang beyond the cold-boot issue that could explain mid-run console stalls?
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Any additional flags or orb settings you recommend (timeouts/retries) that help once tests are already running?
Happy to provide redacted logs, simctl dumps, and pipeline IDs. I would greatly appreciate any and all tips—this is blocking us from being able to switch over to Xcode 26. Let me know, thanks!