Change in the log format
To make it easier for users to investigate SonarQube logs, the format evolved a little bit ( SONAR-8332 - Add unique HTTP request id to logs Closed ) and they are now split in 4 files - one per JVM ( SONAR-8333 - Split sonar.log into 4 logs files specific to each JVM Closed ):
Main JVM (app) : sonar.log
Web JVM (web) : web.log
Compute Engine JVM (ce) : ce.log
Elasticsearch JVM (es) : es.log
All parameters are fully documented in the "sonar.properties" file.
Generic Test Coverage functionality is now a SonarQube core feature
If you were using the Generic Test Coverage plugin, you can remove it when upgrading to SonarQube 6.2+ (having it won't fail the SonarQube startup, it will just be ignored). This is now a built-in feature (see MMF-193 - Absorb Generic Test Coverage plugin functionality into SonarQube core Closed ).
Update of quality gates that use overall or integration test coverage
SonarQube 6.2 now has only one type of coverage ( MMF-345 - Simplify code coverage support in SonarQube Closed ) which merges unit, integration and overall coverage that were badly managed depending on which language(s) and kind of projects you are using. If you had defined quality gate conditions on integration or overall coverage metrics, those quality gates will be automatically updated to use the "default" coverage metric. In this case, you should review those quality gates to make sure that they still represent your requirements.
As a side note, if you were using the Web API to query the overall or integration coverage metrics, you should update your scripts.
Customisable global dashboards and widgets are removed ( SONAR-8354 - Remove dashboards & widgetsClosed). As a consequence, custom plugins which were contributing widgets or dashboards won't be effective any more (but they won't fail SonarQube startup, they will just be ignored).
Web session timeout is configurable through a new property ( SONAR-8298 - Ability to configure timeout of web sessionsClosed)
HTTP-header based authentication is now a built-in feature ( SONAR-5430 - User authentication by HTTP headerClosed) - which allows to implement SSO for SonarQube.