The Technical Debt plugin is no longer compatible with SonarQube 4.0. Technical Debt computation is now directly implemented in SonarQube.
The SQALE plugin has to be manually upgraded to version 2.0 before the SonarQube upgrade.
The RCI Metric is Deprecated
The RCI metric is now deprecated.
Standalone Mode - Move from Jetty to Tomcat
All existing filters using the Key criterion have to be updated. For instance, if the value was "*Plugin*" to match all projects containing the word "Plugin", it will have to be updated to "Plugin".
Location of Temporary Files
Temporary files generated on batch side by the analyzer used to be stored in the java.io.tmpdir folder. But the cleanup mechanism was not always properly working. SONAR-4748 fixes this issue and the previous non-deleted files located in the java.io.tmpdir folder can be safely removed.