ERR_429 on Zapier: Looping Error 429 (Rate Limit Exceeded). Root cause: Zapier enforces a hard cap of 100 task executions per minute on paid plans (lower on free). When a Zap triggers itself — for example, a Zap that updates a record in the same app it watches — each update fires a new trigger, creating an infinite loop. The 429 error is Zapier's circuit-breaker: it halts the Zap after detecting the burst and marks all queued tasks as errored. The loop itself is the bug; the 429 is just the symptom. Step 1: Confirm it is a loop, not a burst. Open Zap History (zapier.com → your Zap → History tab). Filter by "Errored" and sort by time. If you see the same record ID appearing 10+ times within a 60-second window, you have a loop. If you see many different record IDs in a burst, you have a legitimate volume spike — skip to Step 4. Step 2: Identify the trigger-action cycle. A loop almost always means your action modifies the same object your trigger watches. Example: trigger = "New or Updated Contact in HubSpot", action = "Update Contact in HubSpot". Every update fires the trigger again. Map your Zap steps on paper and check whether any action writes back to the trigger source. Step 3: Add a Filter step immediately after the trigger. In the Zap editor, click the + icon directly below your trigger and add a Filter by Zapier step. Set the condition: only continue if [Last Modified By] does not contain "Zapier" — most apps stamp automated edits with a system user. Alternatively, filter on a custom field you set only during manual edits (e.g., a checkbox called "Human Edit" that your Zap never touches). Step 4: For legitimate volume spikes, add a Delay step. If the 429 is caused by a real burst (e.g., a CSV import triggering 500 records at once), add a Delay by Zapier step set to "Delay After Queue" with a 1-second delay. This spreads executions over time and keeps you under the per-minute cap. Note: this does not fix loops — it only helps with volume. Step 5: Upgrade your plan or request a rate limit increase. If your legitimate workload consistently exceeds 100 tasks/minute, open Zapier Settings → Billing and upgrade to Team or Company. Enterprise customers can contact Zapier support to negotiate a custom rate limit. Document your average tasks-per-minute from Zap History before the call. Step 6: Re-enable the Zap and monitor for 10 minutes. After applying the filter, turn the Zap back on. Watch Zap History live for 10 minutes. If the same record ID appears more than once, your filter condition is not catching the loop — revisit Step 3 and tighten the filter logic.