Scheduler triggers are not executed as expected

[Dhanunjay]

I’m facing an issue with a Schedule Trigger in a workflow that is configured to run every 15 minutes from 08:00 to 23:00 IST. However, I’ve observed that some scheduled times are being skipped or missed intermittently.
For example, on 2025-04-09, the trigger skipped expected executions at 08:15, 08:45, and 10:00. Other times fired as expected.
We are using queue mode with ECS autoscaling. I have already ensured:

• GENERIC_TIMEZONE=Asia/Kolkata is set in the environment.
• Schedule Trigger uses the same timezone.
• ECS is set with min 2, max 24 workers, and the main instance is separate from workers.
  Is this expected behavior in queue mode due to concurrency or task restart? How can we ensure 100% reliable triggering?
  and There is no explicit error. The Schedule Trigger just doesn’t fire for some intervals.
  
  
  
  
  

Information on your n8n setup

• n8n version: 1.72.1
• **Database :Postgres
• n8n EXECUTIONS_PROCESS setting : main -queue mode
• Running n8n via (Docker, npm, n8n cloud, desktop app): Docker on ECS
• Operating system: Amazon Linux (ECS Fargate)

[jcuypers]

Hi,

Would you happen to use fargate spot instances?

How are your containers sized (cpu/mem)?

Regards
J.

[Dhanunjay]

@jcuypers

mem

Each Worker will have 0.5 CPU and 1 GB memory based on no of jobs running