Ambari Sever 2.5.x set up as an Ambari Views Server (standalone server with a second Ambari Server registered as a remote server) fails when upgraded to version 2.6.0.

ERROR: Error executing schema upgrade, please check the server logs.
ERROR: Error output from schema upgrade command:
ERROR: Exception in thread "main" org.apache.ambari.server.AmbariException: Unable to find any CURRENT repositories.
	at org.apache.ambari.server.upgrade.SchemaUpgradeHelper.executeUpgrade(SchemaUpgradeHelper.java:203)
	at org.apache.ambari.server.upgrade.SchemaUpgradeHelper.main(SchemaUpgradeHelper.java:418)
Caused by: org.apache.ambari.server.AmbariException: Unable to find any CURRENT repositories.
	at org.apache.ambari.server.upgrade.UpgradeCatalog260.getCurrentVersionID(UpgradeCatalog260.java:510)
	at org.apache.ambari.server.upgrade.UpgradeCatalog260.executeDDLUpdates(UpgradeCatalog260.java:194)
	at org.apache.ambari.server.upgrade.AbstractUpgradeCatalog.upgradeSchema(AbstractUpgradeCatalog.java:923)
	at org.apache.ambari.server.upgrade.SchemaUpgradeHelper.executeUpgrade(SchemaUpgradeHelper.java:200)
	... 1 more

ERROR: Ambari server upgrade failed. Please look at /var/log/ambari-server/ambari-server.log, for more details.
ERROR: Exiting with exit code 11.
REASON: Schema upgrade failed.

BUG-78662

After upgrading Ambari from version 2.2.2 or 2.4.2 to 2.5.x, starting or restarting Ambari Server shows a failure message, but Ambari Server is actually started:

[root@hcube1-1n01 ~]# ambari-server start
Using python  /usr/bin/python
Starting ambari-server
Ambari Server running with administrator privileges.
Organizing resource files at /var/lib/ambari-server/resources...
Ambari database consistency check started...
Server PID at: /var/run/ambari-server/ambari-server.pid
Server out at: /var/log/ambari-server/ambari-server.out
Server log at: /var/log/ambari-server/ambari-server.log
Waiting for server start............................................................
DB configs consistency check found warnings. See /var/log/ambari-server/ambari-server-check-database.log
 for more details.
ERROR: Exiting with exit code 1.
REASON: Server not yet listening on http port 8443 after 50 seconds. Exiting.
[root@hcube1-1n01 ~]# less /var/log/ambari-server/ambari
ambari-alerts.log          ambari-eclipselink.log            ambari-server.log     ambari-server.log.zip
ambari-audit.log           ambari-server-check-database.log  ambari-server.log.1   ambari-server.out
ambari-config-changes.log  ambari-server-command.log         ambari-server.log_bk  ambari_upgrade_config_changes
_03-27-2017_18:48:05.json
[root@hcube1-1n01 ~]# less /var/log/ambari-server/ambari-server.log
[root@hcube1-1n01 ~]# less /var/log/ambari-server/ambari-server-check-database.log
[root@hcube1-1n01 ~]#
[root@hcube1-1n01 ~]#
[root@hcube1-1n01 ~]# ambari-server status
Using python  /usr/bin/python
Ambari-server status
Ambari Server running
Found Ambari Server PID: 2055247 at: /var/run/ambari-server/ambari-server.pid
[root@hcube1-1n01 ~]#

So, the server start/restart operation exceeds the default 60 sec. timeout value set for the Ambari web UI..

Increase the server start/restart timeout value to at least 120 seconds, by changing the value of the following property:

server.startup.web.timeout=120

in

ambari.properties

then, try the start or restart operation again..

BUG-75707

Log Search Server Start fails after upgrade from Ambari 2.4.x to 2.5 with the following errror message:

Client Not Found in Kerberos Database

Regenerate Keytabs after completing upgrade and post upgrade steps to upgrade server, metrics, log search and infra components.

BUG-78170

Hive Visual Explain Plan not loading in Firefox v.31 on SLES 12; returns the following Error message:

TypeError: Object.assign is not a function
...ect.keys(e)[0],a=Object.assign({},e[t],{_operator:t});return a.children?Array.is... 

Use Firefox v 34 (or latest stable version) to run the Hive Visual Explain Plan

BUG-77837

Hive Visual Explain Plan not working in the Internet Explorer or Edge browsers.

Use the Chrome or Firefox browser to work with the Hive Visual Explain Plan feature.

BUG-66998

After changing hadoop.proxyuser.knox.groups or hadoop.proxyuser.knox.hosts to access hive2 through knox, the following error message displays:

Error: Failed to validate proxy privilege of knox_dv for v999003
 (state=08S01,code=0)

Restart the Hive service, so that it operates using these updated core-site configurations.

BUG- 65357

Ambari Server start fails due to Database Consistency Check throwing NullPointerException:

2016-08-31 21:52:28,082 INFO - * Check database started *
2016-08-31 21:52:31,647 INFO - Checking for configs not mapped to any cluster
2016-08-31 21:52:31,653 INFO - Checking for configs selected more than once 
2016-08-31 21:52:31,655 INFO - Checking for hosts without state
2016-08-31 21:52:31,657 INFO - Checking host component states count equals
 host component desired states count 
2016-08-31 21:52:31,660 INFO - Checking services and their configs 
2016-08-31 21:52:33,669 ERROR - Unexpected error, database check failed
 java.lang.NullPointerException at
 org.apache.ambari.server.checks.DatabaseConsistencyCheckHelper
.checkServiceConfigs (DatabaseConsistencyCheckHelper.java:543)
 at org.apache.ambari.server.checks.DatabaseConsistencyChecker.main
(DatabaseConsistencyChecker.java:115)

To start Ambari and avoid this exception, you can start without performing the database consistency check.

ambari-server start --skip-database-check

See Start the Ambari Server for more information about the consistency check.

BUG-63623

After restarting Hive Server Interactive, old, calculated values based on earlier YARN configs are applied for HSI restart. This happens because the HSI configs are not re-calculated on RESTART HSI.

User will have to manually trigger the HSI/LLAP re-calculation.