Webhook Is Sending Duplicate Data: Why the Same Request May Run More Than Once
When a webhook is sending duplicate data, the same request runs more than once. The cause is repeated triggers, workflow re-entry, duplicate source events or automatic retries. Do not assume every repeated request is caused by retries. Trace the source first, because the fix depends on which cause produced the duplicate.
Table of Contents
- 01.Why a webhook sends twice
- 02.What to check first
- 03.Repeated triggers and re-entry
- 04.Duplicate source events
- 05.Automatic retries
- 06.Multiple webhooks and unique identifiers
- 07.How to test it
Why a webhook sends twice
A duplicate webhook means the same request was sent more than once. The cause is either the source event firing more than once or the workflow running the webhook action more than once. Retries are one possible cause but not the only one. Trace the source before assuming retries, because the fixes are different. A retry problem is fixed at the endpoint or retry config. A trigger problem is fixed at the workflow.
| Cause | What happens | How to confirm |
|---|---|---|
| Repeated trigger | Workflow runs twice | Two runs in workflow history |
| Re-entry | Contact re-enters workflow | Re-entry enabled |
| Duplicate source event | Source fired twice | Two events in source log |
| Automatic retries | Endpoint failed, retried | Endpoint returned error first |
| Multiple webhooks | Two webhook actions configured | Two webhook actions in workflow |
What to check first
- Count how many times the webhook request was sent for one event.
- Check the workflow history for repeated runs.
- Check the source event log for repeated source events.
- Confirm whether re-entry is enabled on the workflow.
- Check whether the endpoint returned an error that triggered a retry.
Repeated triggers and re-entry
If the workflow ran twice, the trigger fired twice or the contact re-entered. Check the workflow history for repeated runs. A trigger that fires on an event that occurs twice sends the webhook twice. Re-entry allows the contact to run the webhook action again. Confirm the trigger count and the re-entry setting. This is the same diagnosis covered in the guide on automation running twice.
Duplicate source events
The source event itself may have fired twice. A form submitted twice or a system event that fired twice produces two legitimate triggers. Check the source log to count the source events. If the source fired twice, the fix is at the source, not the webhook. The workflow correctly sent a webhook for each source event.
Automatic retries
Some platforms retry a webhook when the endpoint returns an error. If the endpoint returned an error on the first request, the platform may have retried, producing a duplicate. Check whether the first request returned an error status. If it did, the retry is the cause and the fix is to make the endpoint return a success status, or to make the receiving system idempotent so duplicates do not cause harm. Retry behavior varies by platform, so confirm how yours handles failed requests.
Multiple webhooks and unique identifiers
If two webhook actions are configured in the same workflow or in two workflows, each sends once and the combined result is a duplicate. Check for multiple webhook actions. Unique identifiers help the receiving system handle duplicates. If the payload includes a unique identifier, the receiving system can ignore duplicates by checking whether it already processed that identifier. This makes the system resilient to duplicate requests regardless of cause.
How to test it
- 1.Trigger one source event and count the webhook requests sent.
- 2.Check the workflow history for repeated runs.
- 3.Check the source log for repeated source events.
- 4.Confirm the re-entry setting on the workflow.
- 5.Check whether the first request returned an error that triggered a retry.
- 6.Check for multiple webhook actions in the workflow.
Frequently Asked Questions
Why is my webhook sending duplicate data?
The trigger may fire twice, the contact may re-enter the workflow, the source event may have fired twice or the endpoint may have returned an error that triggered a retry. Trace the source and check the workflow history before assuming retries.
How do I stop my webhook from sending duplicate requests?
Confirm the trigger fires once, disable unwanted re-entry and check for duplicate source events. If retries are the cause, make the endpoint return a success status or make the receiving system idempotent using a unique identifier.
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Related Guides
Automation Running Twice: Why the Same Workflow May Execute More Than Once
Duplicate execution has two causes that look the same. One workflow running twice needs a different fix than two workflows doing the same action. Identify which you have first.
Automation Re-Entry Problems: Why the Same Contact Keeps Entering the Workflow
Re-entry may be legitimate or unwanted. Check the enrollment count, the re-entry setting and the trigger count before deciding whether to block repeated entry.
Automation Webhook Not Firing: A Practical Troubleshooting Guide
A webhook that does not fire either never reached the action or created no request. Determine whether the request was created before debugging the endpoint.