# 52102: Invalid GCM/FCM registration token

Log Level: ERROR

## Description

### Possible causes

* Invalid GCM/FCM registration token provided via the Android SDK or the REST API.

### Possible solutions

* Make sure you do not modify the registration token before providing it to Twilio via the SDK or the REST API.
* If you are using a command line tool to provide the registration token, make sure that it is URL-encoded.