Failure Log: Google Sheets Trigger Feedback Loop
Failure Log: Google Sheets Trigger Feedback Loop
This failure often sounds like:
“We only changed one thing. Then it kept running.”
A Google Apps Script was triggered by edits to a Sheet.
The script itself edited that same Sheet.
Each run triggered the next one.
- Scripts running repeatedly
- Data being overwritten multiple times
- Execution quotas being hit
- The automation being turned off to stop the damage
The trigger observed changes it also created.
There was no distinction between:
- Human edits
- Script edits
The system could not tell the difference.
Why This Was Not Obvious
From the user’s perspective, nothing unusual was happening.
From the system’s perspective, everything was happening.
- Separate detection from processing
- Add guard conditions
- Track execution state
- Ensure script edits do not re-trigger logic
This is a design fix, not a workaround.
Explicit trigger boundaries.
If the system cannot tell who caused the change, it cannot behave safely.
This post documents a real automation failure mode. Similar failures often appear under labels such as trigger feedback loops and self-triggering workflows.
Want to see how we build to prevent these? Read our Designing for Failure technical case study.
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