Firebase FCM 给出结果“错误”：“无效注册”

Question

这是我使用 kotlin 协程请求结果的函数。

private fun sendNotificationToUser(boardName: String, token: String): String {
        var result: String

        var connection: HttpURLConnection? = null
        try {
            val url = URL(Constants.FCM_BASE_URL)
            connection = url.openConnection() as HttpURLConnection

            connection.doOutput = true
            connection.doInput = true
            connection.instanceFollowRedirects = false
            connection.requestMethod = "POST"
            connection.setRequestProperty("Content-Type", "application/json")
            connection.setRequestProperty("charset", "utf-8")
            connection.setRequestProperty("Accept", "application/json")
            connection.setRequestProperty(Constants.FCM_AUTHORIZATION, "${Constants.FCM_KEY}=${Constants.FCM_SERVER_KEY}")
            connection.useCaches = false

            val wr = DataOutputStream(connection.outputStream)

            val jsonRequest = JSONObject()
            val dataObject = JSONObject()
            dataObject.put(Constants.FCM_KEY_TITLE, "Assigned to the Board $boardName")
            dataObject.put(Constants.FCM_KEY_MESSAGE, "You have been assigned to the new board by ${mAssignedMembersList[0].name}")

            jsonRequest.put(Constants.FCM_KEY_DATA, dataObject)
            jsonRequest.put(Constants.FCM_KEY_TO, token)

            wr.writeBytes(jsonRequest.toString())
            wr.flush()
            wr.close()

            val httpResult: Int =
                connection.responseCode

            if (httpResult == HttpURLConnection.HTTP_OK) {

                val inputStream = connection.inputStream
                val reader = BufferedReader(InputStreamReader(inputStream))
                val sb = StringBuilder()
                var line: String?
                try {
                    while (reader.readLine().also { line = it } != null) {
                        sb.append(line + "\n")
                    }
                } catch (e: IOException) {
                    e.printStackTrace()
                } finally {
                    try {
                        inputStream.close()
                    } catch (e: IOException) {
                        e.printStackTrace()
                    }
                }
                result = sb.toString()
            } else {
                result = connection.responseMessage
            }

        } catch (e: SocketTimeoutException) {
            result = "Connection Timeout"
        } catch (e: Exception) {
            result = "Error : " + e.message
        } finally {
            connection?.disconnect()
        }

        return result
    }

谁能告诉我出现此错误的可能原因是什么以及如何解决这些不同的错误。

这是我得到的最终结果 -> {“multicast_id”：4389386151184574869，“成功”：0，“失败”：1，“canonical_ids”：0，“结果”：[{“错误”：“无效注册”}]}