PolarDB为什么突然不能读取到binlog了？

PolarDB为什么突然不能读取到binlog了？[16:47:25.080] ERROR 8210 - io.debezium.connector.mysql.MySqlStreamingChangeEventSource.logStreamingSourceState: Error during binlog processing. Last offset stored = null, binlog reader near position = /4
[16:47:25.080] ERROR 8210 - io.debezium.connector.mysql.MySqlStreamingChangeEventSource.logStreamingSourceState: Error during binlog processing. Last offset stored = null, binlog reader near position = /4
[16:47:25.084] ERROR 8210 - io.debezium.pipeline.ErrorHandler.setProducerThrowable: Producer failure
io.debezium.DebeziumException: Cannot replicate because the master purged required binary logs. Replicate the missing transactions from elsewhere, or provision a new slave from backup. Consider increasing the master's binary log expiration period. To find the missing transactions, see the master's error log or the manual for GTID_SUBTRACT. Error code: 1236; SQLSTATE: HY000.
at io.debezium.connector.mysql.MySqlStreamingChangeEventSource.wrap(MySqlStreamingChangeEventSource.java:1194) ~[debezium-connector-mysql-1.9.7.Final.jar!/:1.9.7.Final]
at io.debezium.connector.mysql.MySqlStreamingChangeEventSource$ReaderThreadLifecycleListener.onCommunicationFailure(MySqlStreamingChangeEventSource.java:1239) [debezium-connector-mysql-1.9.7.Final.jar!/:1.9.7.Final]
at com.github.shyiko.mysql.binlog.BinaryLogClient.listenForEventPackets(BinaryLogClient.java:1079) [mysql-binlog-connector-java-0.27.2.jar!/:0.27.2]
at com.github.shyiko.mysql.binlog.BinaryLogClient.connect(BinaryLogClient.java:631) [mysql-binlog-connector-java-0.27.2.jar!/:0.27.2]
at com.github.shyiko.mysql.binlog.BinaryLogClient$7.run(BinaryLogClient.java:932) [mysql-binlog-connector-java-0.27.2.jar!/:0.27.2]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_121]
Caused by: com.github.shyiko.mysql.binlog.network.ServerException: Cannot replicate because the master purged required binary logs. Replicate the missing transactions from elsewhere, or provision a new slave from backup. Consider increasing the master's binary log expiration period. To find the missing transactions, see the master's error log or the manual for GTID_SUBTRACT.
at com.github.shyiko.mysql.binlog.BinaryLogClient.listenForEventPackets(BinaryLogClient.java:1043) ~[mysql-binlog-connector-java-0.27.2.jar!/:0.27.2]
... 3 more