KSQL server failed to start after upgrade

One small problem after a Kafka cluster upgrade

I just upgraded a small Confluent Kafka cluster at a customer. Almost everything went fine, just following these instructions: https://docs.confluent.io/current/installation/upgrade.html (our servers are running on CentOS). But at the end KSQL server wouldn’t start and failed with this error message: [2019-07-11 16:23:31,233] ERROR Failed to start KSQL (io.confluent.ksql.rest.server.KsqlServerMain:53) java.lang.IllegalStateException: Invalid replcation factor on topic _confluent-ksql-default__command_topic: 1 at io.confluent.ksql.rest.util.KsqlInternalTopicUtils.ensureTopic(KsqlInternalTopicUtils.java:91) at io.confluent.ksql.rest.server.KsqlRestApplication.initialize(KsqlRestApplication.java:237) at io.confluent.ksql.rest.server.KsqlRestApplication.startKsql(KsqlRestApplication.java:200) at io.confluent.ksql.rest.server.KsqlRestApplication.start(KsqlRestApplication.java:187) at io.confluent.ksql.rest.server.KsqlServerMain.tryStartApp(KsqlServerMain.java:65) at io.confluent.ksql.rest.server.KsqlServerMain.main(KsqlServerMain.java:51) I checked the replication factor with: [Read More]