關於「subscribeToTopic」標籤，搜尋引擎有相關的訊息討論：

Topic messaging on Android - Firebase - Googlefirebase.google.com › Documentation › FCMTrying to subscribe to topic on Firebase Cloud Messaging gives Errorstackoverflow.com › questions › trying-to-subscribe-to-top...FirebaseMessaging - Googlefirebase.google.com › docs › android