Why are users in my Customer Journey failing to receive pushes with a 'device not found' error?

Customer Journey drop-offs are reported per element with a specific reason. Double-click the point on a launched Journey to see the reasons and counts. Three of them look similar but have different causes, so start by confirming which one you actually have.

Device not found

The HWID targeted by the Journey is unknown to Pushwoosh: the device was never registered, or its record was deleted. Common causes:

• The user installed the app but never opened it, so no device was registered — yet the entry event was somehow triggered (for example from your backend).
• The HWID lives in your own system and was never passed to Pushwoosh.
• The device record was erased, for example with the Device API /deleteDevice method.

Fix: review the device registration flow and make sure the HWIDs you target are valid and registered.

User not found

The UserID entering the Journey is unknown or was deleted. Typical causes are the same as above but at the user level, plus one email-specific case: if you use an email address as the UserID, your development team must associate that address with the UserID so Pushwoosh treats the user and the email recipient as the same person.

User mismatch

The device's current UserID no longer matches the UserID the user entered the Journey with — typically after a logout/login that reassigns the UserID, or when the same UserID value is reused for a different person.

Fix: keep the UserID stable for the lifetime of a user, and never transfer a UserID value to another person while a device is inside a Journey.

A note on unregistering devices

Explicitly removing devices is rarely necessary. If you do:

• /unregisterDevice (and the SDK's unregisterForPushNotifications()) only clears the push token — the device record and its data stay in Pushwoosh, so the user remains addressable on other channels.
• /deleteDevice fully removes the device and all its data. This is the call that produces later "Device not found" drop-offs.

In most cases it is better to let a stale push token simply become invalid — Pushwoosh handles that automatically — than to delete the device, so the profile survives for when the user re-enables notifications.

Backend-sourced data

If you send user data or trigger events from your own systems, make sure the UserID and device identifiers you pass are current. Stale identifiers are the most common source of all three errors above.