So initially i have physical replication configured, so to upgrade slave to 9.6 version i did converted master slave to logical replication and then try to upgrade the slave to 9.6. I am getting this error when i try to start the slave. Any idea?
2017-11-08 05:08:49 UTC [20063]: [1-1] user= db= host= LOG: shutting down
2017-11-08 05:08:49 UTC [20063]: [2-1] user= db= host= LOG: database system is shut down
2017-11-08 05:09:45 UTC [20322]: [1-1] user= db= host= LOG: database system was shut down at 2017-11-08 05:08:55 UTC
2017-11-08 05:09:45 UTC [20322]: [2-1] user= db= host= LOG: entering standby mode
2017-11-08 05:09:45 UTC [20322]: [3-1] user= db= host= WARNING: WAL was generated with wal_level=minimal, data may be missing
2017-11-08 05:09:45 UTC [20322]: [4-1] user= db= host= HINT: This happens if you temporarily set wal_level=minimal without taking a new base backup.
2017-11-08 05:09:45 UTC [20322]: [5-1] user= db= host= FATAL: hot standby is not possible because wal_level was not set to "replica" or higher on the master server
2017-11-08 05:09:45 UTC [20322]: [6-1] user= db= host= HINT: Either set wal_level to "replica" on the master, or turn off hot_standby here.
2017-11-08 05:09:45 UTC [20312]: [3-1] user= db= host= LOG: startup process (PID 20322) exited with exit code 1
2017-11-08 05:09:45 UTC [20312]: [4-1] user= db= host= LOG: aborting startup due to startup process failure
2017-11-08 05:09:45 UTC [20312]: [5-1] user= db= host= LOG: database system is shut down