Plan version upgrade.
HubSpot Developer Platform 2026.03 Upgrade
The 2026.03 platform version is central to current migration docs. Check `hsproject.json`, current `platformVersion`, and supported migration path before making changes.
Last source check: 2026-05-24
Independent educational guide. Not affiliated with, endorsed by, or sponsored by HubSpot. Verify critical commands and platform behavior against official HubSpot documentation before deploying.
What to inspect
Look for `hsproject.json` and its `platformVersion` property before discussing a `2026.03` upgrade. The migration overview explains how existing platform versions relate to `2026.03`, including cases where no migration is necessary and cases where older versions need more careful review.
A platform-version upgrade is not the same as the May/June 2026 legacy public app creation sunset. The creation sunset affects new legacy public app creation. The `2026.03` workstream affects project structure, platform version, and supported feature migration paths.
If the project is already on `2026.03`, record that and check whether there is any separate Marketplace, CI, or CRM card work. If it is on an older version, open the latest-platform migration docs before changing files or running commands.
Planning a version review
Create a small inventory: current platform version, app type, serverless functions, app cards, static auth or OAuth, Marketplace status, and CI upload flow. This keeps version work tied to actual app features.
For apps on `2025.2`, HubSpot's latest-platform docs describe updating `platformVersion` and re-uploading as part of the 2026.03 path. For older project versions, the docs describe migration guidance that should be followed from the current official page.
Do not apply public app assumptions to private app cases. The latest-platform docs include a private-app limitation for legacy non-project-based private apps, so those cases should be flagged for manual review.
Handoff output
A useful handoff states the current version, the target version to verify, the command or file change to review, and the official docs used. It also lists features that could change migration complexity, such as serverless functions or app cards.
Keep the recommendation reversible until a developer has run the current preflight. The language should be 'likely path to verify,' not 'guaranteed upgrade path.'
Add a source-check date. This repository's official source archive was checked on 2026-05-24, and production decisions should re-open current HubSpot docs.
Checklist
- Record current `platformVersion`.
- Check whether the project is already on 2026.03.
- Review serverless function and app-card implications.
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