Upcoming breaking change: Conversations API, Help Desk, and Comments

HubSpot is in the process of replacing thread comments in Help Desk with notes. This update makes the experience more consistent in HubSpot, using the same notes that users have already been creating on CRM records across more features and tools.

To facilitate this change, we're making some changes to the Conversations API.

What's changing?

This update affects the POST /conversations/v3/conversations/threads/{threadId}/messages endpoint when used with "type": "COMMENT" to add comments to conversation threads.

For threads for a channel account associated with an inbox with "type": "HELP_DESK", this endpoint will begin returning an error when creating comments beginning on September 23,2026.

The error will be a VALIDATION_ERROR with a message that publishing comments is prohibited:

For these threads, you should move to using notes instead. Notes should be created using the CRM Notes API and associated with the ticket in the associatedTicketId in the thread details. If your integration reads existing comments, you should instead begin getting the existing notes associated with the ticket.

For threads in a conversations inbox, there are no changes at this time, and integrations can continue to create comments.

You can check for the error message included above to determine if you should create a note instead of the comment, otherwise you can determine if the thread is in a conversation inbox or help desk:

• Check the originalChannelAccountId in the thread details.
• Get the inboxId for the channel account by its ID.
• Check the type property in the inbox details.

Currently, the update from using comments to using notes in Help Desk is in public beta for HubSpot users. After updating your integration to use notes, you should also send this product update link to your integration users to make sure they can see the notes created by your integration. Users that are not opted into the public beta will see the notes when this feature is released to all users in the near future.

When is this happening?

Integrations will begin receiving an error when creating comments on help desk threads beginning on September 23, 2026.

Comments will continue to be visible to HubSpot users in Help Desk during this migration, and will continue to appear in Help Desk after the migration to notes is complete, though existing comments will not be migrated to notes.

For more details about Help Desk replacing comments with notes, see this product update.

Please let us know if you have any questions by joining the discussion in our community.