API CHANGELOG

The breaking changes your team needs to know about — Issue #2 • Week of May 17, 2026

⏰ The Deprecation Clock

🚨 Breaking Changes

What breaks: Starting May 21, 2026, T-Mobile A2P 10DLC daily message cap warning error codes 30025 (50% threshold), 30026 (70% threshold), and 30027 (100% of daily limit) will stop firing in API error logs and webhooks. The associated proactive warning emails will also stop.

The fix: If you have webhooks or alerting logic that watches for these error codes, update your monitoring to remove references to 30025, 30026, and 30027. Error code 30023 (which fires when traffic hits 100% of the T-Mobile daily cap) is not affected and will continue to work.

Deadline: May 21, 2026 — 4 days from now. If you rely on these codes for alerting, this is urgent.

Source: Twilio Changelog — Read more

What breaks: Grok Code Fast 1 has been deprecated across all GitHub Copilot experiences — Copilot Chat, inline edits, ask mode, agent mode, and code completions. If you or your team had this model selected, it will no longer be available.

The fix: Switch to an alternative model. GitHub suggests GPT-5 mini or Claude Haiku 4.5 as replacements. Copilot Enterprise administrators should check their model policies in Copilot settings to ensure access to alternative models is enabled for their organisation.

Deadline: Already effective as of May 15, 2026. No transition period.

Source: GitHub Changelog — Read more

👁 Silent Changes

Two image changes to be aware of if you use GitHub Actions hosted runners:

1. Arm64 images now maintained by GitHub. Previously maintained by Arm Limited, now fully managed by GitHub. Windows 11 Arm (windows-11-arm) images have been migrated. Ubuntu images for Arm (ubuntu-24.04-arm, ubuntu-22.04-arm) are transitioning. GitHub says no action is required, but if you pin specific image versions or checksums in your workflows, verify after the transition.

2. Image migrations for hosted runners. Customers should review their workflows if they depend on pre-installed tools at specific versions, since image updates can change the default versions of languages, runtimes, and tooling.

Source: GitHub Changelog — Read more

Why it matters: GitHub is rolling out a new token format for GitHub App installation tokens, announced in April 2026. To help you test before the rollout reaches your apps, GitHub has introduced a temporary override header.

What to do: Set the X-GitHub-Stateless-S2S-Token header on your POST /app/installations/:installation_id/access_tokens requests to force either the new or old token format. Use this to validate that your apps and workflows work with the new format before GitHub flips the switch.

If your code makes assumptions about token format, length, or structure — test now while you still have control over the rollout.

Source: GitHub Changelog — Read more

What's new: Starting with the 2026-07 version of the Storefront API, the Cart will emit a PRODUCT_UNAVAILABLE_IN_BUYER_LOCATION warning when a cart line contains a product that isn't available in the buyer's location.

Why it matters: Each affected cart line returns its own warning with the target set to the CartLine ID, so you can map it to your UI. If your storefront doesn't handle cart warnings today, this new code will arrive silently — your checkout still works, but you'll be missing useful information you could display to customers.

Source: Shopify Changelog — Read more

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