How do you update a flow message template's content using the api

​@Email Pulse, mind sharing the exact error message + status code you’re getting back from the API? Also can you confirm whether the template you’re trying to update is an HTML template? Or is it a drag-and-drop template? Updating the former is supported by the API, while the latter is not (...yet).

Another approach you might try would be to (1) create a new template with the content you want via the Create Template API, (2) patching the send email flow action to reference that new template_id instead (https://developers.klaviyo.com/en/reference/update_flow_action).

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Hey ​@Email Pulse 

I am not 100% sure about this but my hunch is that the template ID returned from Get Flow Message Template isn't a standalone template ID that the Update Template endpoint recognizes. Flow message templates built inside the flow editor seem to be embedded in the flow message itself rather than living in your Templates library, which would explain why Klaviyo throws that error when you try to PATCH api/templates/{id} directly.

If that's the case, the workaround I'd try first is updating the flow message content through the flow action itself rather than the Templates endpoint.

Alternatively, another approach worth trying is cloning the template first using Clone Template, updating the cloned version via Update Template, and then reassigning that updated template back to the flow message through the relationship endpoint.

One thing I'm fairly confident about: the docs do explicitly state that Update Template does not support drag and drop templates, only code-based ones. Since yours is code type you should be clear on that front at least.

I'm not 100% certain which of these paths will work cleanly for your specific setup, so it would really help to see the exact error response you're getting. That would narrow it down quickly.

I hope this helps and thank you for sharing your question here in the community.

Cheers,
Arpit