# Authentication and actionDefinitionVersion lookup for project-based custom workflow actions

**URL:** <https://community.hubspot.com/t/authentication-and-actiondefinitionversion-lookup-for-project-based-custom-workflow-actions/163914>\
**Category:** APIs & Integrations\
**Tags:** api\
**Created:** [November 4, 2026, 2:12am UTC](https://community.hubspot.com/t/authentication-and-actiondefinitionversion-lookup-for-project-based-custom-workflow-actions/163914 "2026-11-04T02:12:45Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![LeonKingsley](https://avatars.discourse-cdn.com/v4/letter/l/ec9cab/32.png) [@LeonKingsley](https://community.hubspot.com/u/LeonKingsley)\
**Post date:** [November 4, 2026, 2:12am UTC](https://community.hubspot.com/t/authentication-and-actiondefinitionversion-lookup-for-project-based-custom-workflow-actions/163914/1 "2026-11-04T02:12:45Z")

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Hello HubSpot developers,

We are testing a project-based private app with static authentication on developer platform version 2026.03. The app requests only `crm.objects.deals.read`. We used HubSpot CLI 8.16.0 with a personal access key limited to `developer.projects.write`; project upload and deployment succeeded.

Before running a custom workflow action, we need to verify the exact numeric `actionDefinitionVersion` expected in its callback. A read-only GET to `/automation/v4/actions/{appId}/{definitionId}`, authenticated through the CLI’s PAK-backed HTTP client, returned HTTP 401 with category `INVALID_AUTHENTICATION`. We have not established the cause. We have not executed the workflow or added credentials or scopes to resolve this.

Could you clarify:

1. Which supported endpoint and authentication method should a project-based private/static app use to read its deployed custom workflow action definition, and what are the minimum permissions? Is a personal access key supported, or is a developer API key required?
2. Which returned field maps to the numeric `actionDefinitionVersion` sent in callbacks? How does it relate to the definition revision, project build number, and project subbuild revision UUID?
3. Can we verify that value before executing the workflow using supported CLI or app-management functionality without adding account-wide credentials?

The temporary test workflow is off, and the test app installation and tunnel have been removed. I have also submitted this question through official support and am looking for a documented approach before another controlled test.

Thank you.

This post was prepared with AI assistance; the reported test observations were checked against our execution records.

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**Author:** ![Berangere](https://d10pqhm3lwygmk.cloudfront.net/user_avatar/community.hubspot.com/berangere/32/220784_2.png) [@Berangere](https://community.hubspot.com/u/Berangere)\
**Post date:** [November 4, 2026, 11:31am UTC](https://community.hubspot.com/t/authentication-and-actiondefinitionversion-lookup-for-project-based-custom-workflow-actions/163914/3 "2026-11-04T11:31:49Z")

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Hi @LeonKingsley and Happy Wednesday!

Great questions, thanks for asking the HubSpot Community!

Let’s consult our Top Experts: Hi @Anton, @evaldas and @nickdeckerdevs1 do you have any insights to share with @LeonKingsley, please?

In the meantime, here are some resources that can help:

- [Retrieve a custom action definition - HubSpot docs](https://developers.hubspot.com/docs/api-reference/2026-03/automation/workflow-actions/definitions/get-action-definition)
- [Custom workflow actions reference - HubSpot docs](https://developers.hubspot.com/docs/api-reference/latest/automation/workflow-actions/custom-action-reference)
- [Define a custom workflow action - HubSpot docs](https://developers.hubspot.com/docs/apps/developer-platform/add-features/custom-workflow-actions)

Have a wonderful day and thanks so much!

Bérangère, HubSpot Community Manager