I'm trying upgrade ambari-server and ambari-agent from 2.2.2 to 2.6 in Centos 7.
Refered to official document , I progressed smoothly until the command "ambari-server upgrade",And the /var/log/ambari-server/ambari-server.log shows:
17 Nov 2017 14:03:37,055 INFO [main] LockFactory:53 - Lock profiling is disabled
17 Nov 2017 14:03:37,062 INFO [main] SchemaUpgradeHelper:394 - Upgrading schema to target version = 126.96.36.199
17 Nov 2017 14:03:37,082 INFO [main] SchemaUpgradeHelper:403 - Upgrading schema from source version = 2.2.2
17 Nov 2017 14:03:37,084 ERROR [main] SchemaUpgradeHelper:437 - Exception occurred during upgrade, failed
org.apache.ambari.server.AmbariException: Database version does not meet minimal upgrade requirements. Expected version should be not less than 2.4.0, current version is 2.2.2
17 Nov 2017 14:05:09,089 INFO [main] AmbariServer:207 - Found org/apache/ambari/server/controller/AmbariServer.class class in file:/usr/lib/ambari-server/ambari-server-188.8.131.52.267.jar!/org/apache/ambari/server/controller/AmbariServer.class
It works! I downgrade Ambari to 2.5.1 and run 'ambari-server upgrade'. After successful completion, I upgrade Ambari to 2.6.0 and run 'ambari-server upgrade' again. This time the server startup without problem. Thank you for the solution.