## TL;DR

Browsers detect the change and kill the stale subscription tied to the old location, which is what was doubling the notifications. Keep service worker locations stable, and when you must move one, always leave the cleanup file behind.

## Steps

1. If Airship web push starts duplicating after you move the service worker, do not resubscribe everyone: drop a cleanup push-worker.js at the worker's previous location that unsubscribes on activate. Browsers detect the change and kill the stale subscription tied to the old location, which is what was doubling the notifications. Keep service worker locations stable, and when you must move one, always leave the cleanup file behind.

## When to use

You are seeing this: If Airship web push starts duplicating after you move the service worker, do not resubscribe everyone: drop a cleanup push-worker.js at the worker's previous location that unsubscribes on activate. Use this skill when you run into "Airship web push duplicates after moving the service worker".

## When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

## Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

## Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.