CircleCI macOS M1 and M2 Resource Class EOL on February 16, — when and how should I migrate?

Teams with Apple-platform CI pipelines need to know which CircleCI macOS configs already broke after the February 16, 2026 retirement and which M4 Pro replacement classes to budget for.

Pin m4pro.medium to restore Apple CI now, unless your jobs are memory-bound or simulator-heavy; use m4pro.large only when medium proves unstable or too slow.

Blockers

Who this is for

Candidates

Pin "m4pro.medium" for standard Apple-platform CI

As of 2026-03-26, CircleCI has already retired the older macOS resource classes "macos.m1.medium.gen1", "macos.m1.large.gen1", "m2pro.medium", and "m2pro.large". CircleCI's current price list shows "m4pro.medium" at "200 credits/min" with "6 CPU" and "28 GB RAM". CircleCI's macOS docs list current M4 Pro support for Xcode "14.3.1", "15.4.0", "16.3.0", "16.4.0", and "26.0.1" through "26.3.0". CircleCI support states jobs that still specify M1 or M2 classes now fail with a configuration error.

When to choose

Use this when you want the lowest-cost supported replacement and your builds fit within the medium M4 Pro footprint. It is the direct successor for teams that were previously on M1 or M2 medium-sized executors and need to get pipelines green again with minimal spend.

Tradeoffs

Lowest supported macOS replacement cost on CircleCI, but less headroom than "m4pro.large" for parallel test shards, large simulators, or memory-heavy Xcode builds.

Cautions

Do not assume older Xcode images survived the migration. CircleCI states Xcode "16.2.0" was deprecated from M4 Pro on "2026-01-14" and was only left on M1/M2 until those classes were retired, so some previously working M1/M2 plus older-Xcode combinations are no longer available.

Sources

Pin "m4pro.large" for faster or memory-heavier macOS jobs

As of 2026-03-26, "m4pro.large" is the larger supported CircleCI macOS replacement class after the M1/M2 retirement. CircleCI's current price list shows "m4pro.large" at "400 credits/min" with "12 CPU" and "56 GB RAM". The same current M4 Pro Xcode matrix applies here, so it supports the listed M4-compatible Xcode versions rather than restoring retired M1/M2-only combinations. This option is the budget target if medium jobs become unstable, too slow, or memory-constrained after migration.

When to choose

Use this when build time, simulator load, or memory pressure makes "m4pro.medium" unreliable or too slow. The decisive factor is whether the extra credits buy enough wall-clock reduction or stability to justify a 2x per-minute compute rate.

Tradeoffs

More CPU and RAM can shorten builds and reduce flaky resource contention, but it doubles the macOS credit burn relative to "m4pro.medium".

Cautions

This is not a compatibility escape hatch for retired M1/M2 Xcode images. If your pipeline depended on an older Xcode version that only existed on M1/M2, moving to large does not bring that version back.

Sources

Remove explicit resource_class and accept CircleCI's default "m4pro.medium"

As of 2026-03-26, CircleCI support states that macOS jobs with no explicit "resource_class" automatically use "m4pro.medium". CircleCI also recorded the default rollout dates: Free plan default changed on "2025-11-10" and paid plan default changed on "2025-12-03", before the final retirement on "2026-02-16". This can be the quickest remediation for repositories that only need a supported default and do not want to pin executor size everywhere. Budget-wise, the underlying default is still the "m4pro.medium" class, so the relevant official compute price remains "200 credits/min" as of 2026-03-26.

When to choose

Use this when you want the smallest config diff and are comfortable with CircleCI's current macOS default. It is most appropriate for simple pipelines where explicit executor sizing is not part of your capacity planning.

Tradeoffs

Fastest migration path, but less explicit than pinning a resource class and easier to overlook in future cost or performance reviews.

Cautions

This only helps jobs that omitted the field. Any config that still explicitly references "macos.m1.medium.gen1", "macos.m1.large.gen1", "m2pro.medium", or "m2pro.large" will continue to fail until changed.

Sources

Facts updated: 2026-03-26
Published: 2026-04-03

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