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Slack API breaking changes (2025–2026): complete tracker and fixes

slack 17 breaking / deprecation entries 2025–2026

Slack ships API and SDK changes continuously. Most are additive — but the ones that are not can silently break integrations that worked yesterday. This page is the complete, continuously regenerated record of every Slack breaking change and deprecation in the mendapi change database: 17 entries (16 breaking, 1 deprecation), each linked to its upstream source and, where possible, to a concrete fix.

How to read this page

Every entry carries a fixability verdict from the mendapi adjudication pipeline: code-fixable means a mechanical code change repairs the break (4 entries); not code-fixable means the change requires a business decision, credential provisioning, or upstream action that no codemod can produce (13 entries). Entries marked auto-fix pack have a deterministic, gold-tested migration pack that mendapi fix can apply locally.

Am I affected?

Reading a changelog tells you what changed — not whether your code uses the affected surface. The mendapi scanner answers that locally, in about 30 seconds, without any code leaving your machine:

npx mendapi sync
# -> one network call: pulls the change feed into a local database
npx mendapi scan
# -> N findings: file, line, provider, confidence
mendapi deps --match
# -> which of the changes below actually hit your endpoints

See Getting Started for the full workflow and the security model for why zero code upload is the default and only mode.

Complete Slack breaking change timeline

Automated migration packs for Slack

mendapi ships 2 deterministic migration packs for Slack — verified, idempotent codemods you can apply locally with mendapi fix. Full details in the pack catalog.

• slack-cli-hooks-file-move — Slack CLI 3.0.0: slack.json relocated to .slack/hooks.json (project config move) (upstream reference)
• slack-sdk-v8-errors — Slack SDK v8 error-handling migration (ErrorCode checks -> instanceof) (upstream reference)

Recent Slack releases adjudicated non-breaking

Not paging you is the other half of the job. The same pipeline that produced the timeline above also cleared 20 Slack changes as additive or fix-only — releases an integrator can upgrade through without a migration. The most recent:

Measured: when the changelog title tells you nothing

The Slack entries above come from two feeds — node-slack-sdk major releases and the api.slack.com changelog — not a spec-diff corridor, so unlike the Stripe or Twilio trackers this page makes no corridor claim. What every entry does carry is an adjudicated fixability verdict with a machine-readable reason, and for Slack the verdicts do work the titles refuse to do: of the 17 breaking and deprecation entries above, 4 are code-fixable and 13 are not — and many of the changelog titles are so generic that only the adjudicated reason says which side an entry lands on.

A verdict that comes with a fix. “@slack/[email protected]” is code-fixable because the migration is enumerable: @slack/web-api v8 error-class redesign with documented ErrorCode->instanceof migration (pack slack-sdk-v8-errors covers it). That is the class of change the slack-sdk-v8-errors migration pack (see the pack catalog) carries as a deterministic, gold-tested codemod.

A title that says nothing, a verdict that does. “New feature: We improved our SDKs and tools” is the changelog's own headline for a breaking flag. The adjudicated reason reads: Slack CLI 3.6.1 stops bundling deno; developer-environment/CI setup, not application code. An unadjudicated feed would page you on the headline; the verdict tells you, with the reason attached, that no application code is affected.

Monitoring Slack going forward

This page is regenerated from the change database, which is fed by release feeds, changelog capture and OpenAPI spec diffing — so it does not depend on Slack writing a perfect changelog. mendapi monitors 84125 change records across 20 providers; hosted plans watch your repos continuously and open fix PRs when a change lands. See pricing.

Frequently asked questions

Related

• API breaking change detection — how upstream breakage is caught before it ships, and why default severity gates stay silent.
• All breaking-change reports — per-change deep dives with migration guides.
• All monitored providers — live change counts.
• Migration pack catalog — every deterministic fix mendapi ships.