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From the brief of Tuesday, October 13, 2026 · No. 4

From the daily brief · Automation

Zapier fixes bug that broke some Custom Actions and MCP requests from Oct. 7 to Oct. 12

If a Zap uses a Custom Action or an AI assistant runs Zapier through MCP, some runs may have failed for five days and need redoing by hand.

By Carter Josephson · · 1 min read

What happened

Zapier says a deploy starting October 7 caused some outbound Custom Actions and Zapier MCP requests to include duplicate query parameters, which a subset of connected apps rejected even when inputs were valid. A fix went out on October 12 at 09:40 UTC; Zapier says standard app actions in Zaps were not affected and it has found no evidence of data loss.

What it means for a 10-to-50-person business

Most Zapier users can skip this. Standard app actions, the prebuilt steps most Zaps use, were not affected. It matters only if a Zap uses a Custom Action, the step you build yourself against an app's API, or if you connect an AI assistant to your apps through Zapier MCP. Example: a 15-person accounting firm uses a Custom Action to create a client record in its practice-management software for each intake form. Assume 6 new clients a day. Over the four working days from Wed. Oct. 7 to Mon. Oct. 12, up to 24 records may never have been created, if that app was one that rejected the duplicated parameters. Zapier says not every app or request failed, and its status page does not say failed runs were retried. So the gap is yours to find. The likely damage is quiet: an intake that never reached the client list, or an invoice or job that was never created.

What to do
Ignore

Nothing needs changing, but if any Zap uses a Custom Action or you use Zapier MCP, filter Zap history for errored runs from Oct. 7 to Oct. 12 this week and rerun or re-enter the ones that matter.

What it costs
What it costs
Zapier plan or setup change
$0
Checking Zap history for Oct. 7–12 errors
30 min (≈ $25 at $50/hr)
Re-entering missed records, assume 24 × 3 min
1.2 hrs (≈ $60 at $50/hr)
Doing nothing
$0 now; any requests rejected Oct. 7–12 stay undone until someone notices a missing record
Sources
status.zapier.com (primary) · Zapier Support: get help

Questions owners ask

Were my normal Zaps affected?

Zapier says standard app actions for connected apps in Zaps were not affected. Only Custom Actions and Zapier MCP requests were affected, and only with some apps.

Did Zapier lose any of my data?

Zapier says it has found no evidence of data loss. The risk is requests that were rejected and never completed, not data that was deleted.

Who do I contact if something still looks wrong?

Zapier asks affected customers to contact its support team at zapier.com/app/get-help.

Three to five of these, every weekday morning.

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