The Timeline API will be undergoing maintenance between 2:00 PM and 2:30 PM Eastern Time Thursday, September 3. During this maintenance period, there will be a brief period where the Timeline API will be unavailable, and any requests to the API will result in HTTP 500 errors. We expect this period to last less than 1 minute, but during this period any attempts to create, update, or fetch timeline events will fail, and those requests will need to be retried.
If your integration retries on 5xx errors, then you shouldn't need to make any major changes for this, as long as your retry period lasts for at least a minute.
If your integration does not currently retry on 5xx errors, then these requests will fail. Updates will not be queued or retried from HubSpot's side, so you will need to log these failed requests and replay them to make sure that all timeline events get created. As a best practice, make sure to set the timestamp to when the event originally occurred
Please let us know if you have any questions by replying to this forum thread.