Describe the problem/error/question
Every webhook sent to n8n triggers **2 executions instead of 1**, occurring within 30-70 milliseconds of each other. This doubles our execution usage, effectively halving our plan limit from 2500 to 1250 webhooks.
Evidence
n8n Instance: https://launchlee.app.n8n.cloud
Workflow: Main-Content (ID: sZeWx6ezgcMYcY2A)
1. Supabase Sends Only 1 Webhook 
Test Date: 2025-09-30 16:31:02
Database Logs:
Webhook logs table shows exactly 1 webhook sent:
- Time: 2025-09-30T16:31:02.448858+00:00
- Record ID: 67fabcd2-f548-491f-a3d5-18f9eed8588e
- Webhook: n8n_action_item_execute
- Payload: 1544 bytes
2. n8n Receives 2 Executions 
n8n Execution History shows duplicate executions:
Time: 2025-09-30 16:31:04+00:00
1. Execution ID: 7159 Started: 2025-09-30T16:31:04.915Z
2. Execution ID: 7158 Started: 2025-09-30T16:31:04.887Z
Time Difference: 28 milliseconds
Time: 2025-09-29 18:07:05+00:00
1. Execution ID: 6566 Started: 2025-09-29T18:07:05.714Z
2. Execution ID: 6565 Started: 2025-09-29T18:07:05.644Z
Time Difference: 70 milliseconds
Time: 2025-09-29 11:35:49+00:00
1. Execution ID: 6126 Started: 2025-09-29T11:35:49.545Z
2. Execution ID: 6125 Started: 2025-09-29T11:35:49.476Z
Time Difference: 69 milliseconds
Pattern:
This occurs **100% of the time** across all recent webhooks.
3. Webhook Configuration
Workflow Details:
- Workflow ID: `sZeWx6ezgcMYcY2A`
- Status: Active
Webhook Node Configuration:
{
“httpMethod”: “POST”,
“path”: “path masked”,
“authentication”: “headerAuth”,
“options”: {
“rawBody”: “{\“status\”: \“received\”, \“timestamp\”: \”{{$now}}\“}”,
“responseHeaders”: {
“entries”: [
{"name": "Content-Type", "value": "application/json"}
\]
}
}
}
**Key Observations**:
- 
Response Mode: Not explicitly set (missing `responseMode` option)
- Only 1 active workflow uses this webhook path
- No duplicate webhook nodes in workflow
- No other workflows with similar paths
4. Community Reports
imilar issues reported in n8n community:
- [Webhook executions multiply]( Webhook executions multiply and get stuck at “Starting soon” on n8n Cloud · Issue #18929 · n8n-io/n8n · GitHub ) - Marked as support issue
- Multiple users reporting duplicate webhooks milliseconds apart
Root Cause Analysis
Based on investigation, this appears to be an n8n Cloud infrastructure issue:
Possible issue:
1. Load Balancer Duplication: Webhook might be hitting multiple n8n instances behind load balancer
2. Internal Webhook Registration: Webhook path might be registered twice in n8n Cloud
3. Multi-Process Handling: Same webhook being processed by multiple worker processes
This is NOT:
- Supabase sending duplicate webhooks (proven with logs)
- Multiple workflows with same path (verified only 1 exists)
- User configuration error (webhook config is correct)
- Retry logic (executions are simultaneous, not sequential)
Business Impact
- Cost: Effectively paying 2x for execution usage
- Blocking Issue: Cannot scale beyond 1250 webhooks without upgrade
Requested Action
Please investigate n8n Cloud infrastructure for this workflow:
- Check webhook routing/load balancer configuration
- Verify webhook registration is single, not duplicate
- Review multi-instance webhook handling
If needed, I can provide:
- Full webhook logs from Supabase
- Complete execution history from n8n
- Network traces from webhook sender
- Workflow JSON export
Information on your n8n setup
- n8n version: latest (cloud)
- Database (default: SQLite):
- n8n EXECUTIONS_PROCESS setting (default: own, main): default
- Running n8n via (Docker, npm, n8n cloud, desktop app): cloud
- Operating system: MAC
