Users are experiencing issues with Shopify Flow automations that successfully trigger and tag orders but fail to send follow-up emails to customers. The workflows get stuck in ‘Running’ status.
Root Cause Identified:
The error message “No outstanding balance exist” appears when using the “send invoice” action on orders that are already paid in full. Shopify Flow’s invoice action requires an outstanding balance to function.
Key Problem:
Shopify Flow doesn’t natively support sending general follow-up emails to customers after order placement—only invoice-related communications.
Workaround Solution:
One user resolved this by switching to Klaviyo, which offers a free tier supporting up to 500 emails per month. While not ideal (requires another app subscription), it provides the needed functionality for post-purchase customer emails.
Status:
Multiple users confirm experiencing the same issue. No native Shopify Flow solution exists for this use case.
I have a flow that detects new orders with a particular line item in them. The flow tags the order and then it’s supposed to auto send an email to the customer. It adds the tag, so the trigger seems to be working fine. However it’s status is stuck on ‘running’ and I can’t work out why. Attached is a screenshot of the email flow, which seems to be good as far as I can tell, but obviously something is off.
Any ideas on why this is stuck? I don’t want to manually send all these customer emails 
I just realized that my other workflow is doing the same thing. It recognizes the trigger- tags the order but fails to send the customer the email. In this case, its when the ship-to address is a PO Box, its supposed to send an email asking for an alternate shipping address. I just did a test order and it tagged the order correctly, but never emailed me requesting a new address.
UPDATE - the error message I’m getting is “Ran into transient error: GraphQL Response User Errors: “No outstanding balance exist”” I think because I picked “send invoice” it errors out because the order is paid in full.
Apparently Flow doesn’t support sending a follow up email to a customer after an order is placed. I am not interested in using another app subscription.
Hello,
we’re running into the same problem. Would be interesting, if someone has a solution for this. 
Hi Daniel,
As much as I don’t want to use another app - it looks like we may be using the Klaviyo app. Their free version allows us more than enough emails per month (500) for this scenario. Not the solution I’d hoped for- but it’ll do!
