This is the relevant log:
2016.03.16 16:11:01 INFO web[o.s.s.p.w.RestartAction] SonarQube restart requested by admin
2016.03.16 16:11:01 INFO app[o.s.p.m.Monitor] Process [web] requested restart
2016.03.16 16:11:01 INFO app[o.s.p.m.Monitor] Process[web] is stopping
2016.03.16 16:11:02 INFO web[o.s.p.StopWatcher] Stopping process
2016.03.16 16:11:02 INFO web[o.a.c.h.Http11NioProtocol] Pausing ProtocolHandler ["http-nio-0.0.0.0-80"]
2016.03.16 16:11:03 INFO web[o.a.c.h.Http11NioProtocol] Pausing ProtocolHandler ["http-nio-0.0.0.0-443"]
2016.03.16 16:11:04 INFO web[w.s.NegotiateSecurityFilter] [waffle.servlet.NegotiateSecurityFilter] stopped
2016.03.16 16:11:04 INFO web[o.s.s.n.NotificationService] Notification service stopped
2016.03.16 16:11:05 INFO web[o.a.c.h.Http11NioProtocol] Stopping ProtocolHandler ["http-nio-0.0.0.0-80"]
2016.03.16 16:11:05 INFO web[o.a.c.h.Http11NioProtocol] Stopping ProtocolHandler ["http-nio-0.0.0.0-443"]
2016.03.16 16:11:06 INFO web[o.a.c.h.Http11NioProtocol] Destroying ProtocolHandler ["http-nio-0.0.0.0-80"]
2016.03.16 16:11:06 INFO web[o.a.c.h.Http11NioProtocol] Destroying ProtocolHandler ["http-nio-0.0.0.0-443"]
2016.03.16 16:11:06 INFO web[o.s.s.a.TomcatAccessLog] Web server is stopped
Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=160m; support was removed in 8.0
2016.03.16 16:11:06 INFO app[o.s.p.m.Monitor] Process[web] is stopped
2016.03.16 16:11:06 INFO app[o.s.p.m.Monitor] Process[search] is stopping
2016.03.16 16:11:07 INFO es[o.s.p.StopWatcher] Stopping process
2016.03.16 16:11:07 INFO es[o.elasticsearch.node] [sonar-1457639022997] stopping ...
2016.03.16 16:11:07 INFO es[o.elasticsearch.node] [sonar-1457639022997] stopped
2016.03.16 16:11:07 INFO es[o.elasticsearch.node] [sonar-1457639022997] closing ...
2016.03.16 16:11:07 INFO es[o.elasticsearch.node] [sonar-1457639022997] closed
2016.03.16 16:11:07 INFO app[o.s.p.m.Monitor] Process[search] is stopped
2016.03.16 16:11:07 INFO app[o.s.a.AppFileSystem] Cleaning or creating temp directory C:\Sonar\sonarqube-5.4\temp
Exception in thread "Restartor 0" java.lang.RuntimeException: Failed to reset file system
at org.sonar.process.monitor.Monitor.resetFileSystem(Monitor.java:125)
at org.sonar.process.monitor.Monitor.startProcesses(Monitor.java:105)
at org.sonar.process.monitor.Monitor.access$500(Monitor.java:38)
at org.sonar.process.monitor.Monitor$RestartorThread.run(Monitor.java:282)
Caused by: java.nio.file.FileSystemException: C:\Sonar\sonarqube-5.4\temp\sharedmemory: The process cannot access the file because it is being used by another process.
at sun.nio.fs.WindowsException.translateToIOException(Unknown Source)
at sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source)
at sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source)
at sun.nio.fs.WindowsFileSystemProvider.implDelete(Unknown Source)
at sun.nio.fs.AbstractFileSystemProvider.delete(Unknown Source)
at java.nio.file.Files.delete(Unknown Source)
at org.sonar.process.FileUtils$CleanDirectoryFileVisitor.visitFile(FileUtils.java:151)
at org.sonar.process.FileUtils$CleanDirectoryFileVisitor.visitFile(FileUtils.java:135)
at java.nio.file.Files.walkFileTree(Unknown Source)
at org.sonar.process.FileUtils.cleanDirectoryImpl(FileUtils.java:123)
at org.sonar.process.FileUtils.cleanDirectory(FileUtils.java:60)
at org.sonar.application.AppFileSystem.createOrCleanDirectory(AppFileSystem.java:116)
at org.sonar.application.AppFileSystem.reset(AppFileSystem.java:73)
at org.sonar.process.monitor.Monitor.resetFileSystem(Monitor.java:122)
... 3 more
Solution: Restart SonarQube windows service yourself.