I\'m trying to find out if there are any limitations for the topic names for FCM. Managed to find info about the number of topics (no limitations), but nothing like length o
Yes, not all characters are allowed, having space between words is not allowed in topic names.
From the docs:
sending messages to a Firebase Cloud Messaging topic is very similar to sending messages to an individual device or to a user group. The app server sets the topic key in the message body with a value like
yourTopic. Developers can choose any topic name that matches the regular expression: "[a-zA-Z0-9-_.~%]+"
for more info check this: https://firebase.google.com/docs/cloud-messaging/android/topic-messaging (build request section)