> For the complete documentation index, see [llms.txt](https://docs.quickreply.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.quickreply.ai/overview/messaging-channels/rich-communication-service-rcs/error-from-rcs/error-user-not-found.md).

# 🚫 Error: User Not Found

#### Error: User Not Found

When sending an RCS message, you may occasionally encounter the error “User Not Found.”

This error indicates that the recipient could not be reached through RCS for Business.

### What Does This Error Mean?

RCS for Business checks whether a phone number can be reached through RCS before delivering a message.

If the RCS platform cannot reach the recipient, the user may be returned as “Not Found.” Google's RCS for Business documentation states that a 404 NOT\_FOUND response can occur when a user cannot be reached through RCS. This includes situations where the user's device does not support RCS or has RCS disabled, or where the user's mobile network is not configured for the agent or RCS traffic.

### Why This Error Happens

The error can occur when:

* The recipient cannot be reached through RCS.
* The recipient's device does not support RCS.
* RCS is disabled on the recipient's device.
* The recipient is on a mobile network where the RCS Agent is not launched or RCS traffic is not enabled.

### How to Handle This Error

If the recipient cannot be reached through RCS, the message cannot be delivered through the RCS channel.

If Delivery Optimization is enabled, configure a fallback channel such as WhatsApp or SMS. QuickReply can continue delivery through the configured fallback channel when the RCS delivery attempt fails.

For more information, see How to Use RCS Broadcast Delivery Optimization.

### Final Note

“User Not Found” does not necessarily mean that the phone number is invalid. It means that the recipient could not be reached through RCS for Business at the time of the delivery attempt.

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