Since a recent update (2-3 days ago) this error appears in the console every time fiji is started:
---------------
[ERROR] Module threw exception
java.lang.IllegalStateException: Context already injected: net.imagej.updater.CheckForUpdates#commandService
	at org.scijava.Context.inject(Context.java:440)
	at org.scijava.Context.inject(Context.java:382)
	at org.scijava.command.CommandModule.initialize(CommandModule.java:146)
	at org.scijava.module.process.InitPreprocessor.process(InitPreprocessor.java:61)
	at org.scijava.module.ModuleRunner.preProcess(ModuleRunner.java:104)
	at org.scijava.module.ModuleRunner.run(ModuleRunner.java:156)
	at org.scijava.module.ModuleRunner.call(ModuleRunner.java:126)
	at org.scijava.module.ModuleRunner.call(ModuleRunner.java:65)
	at org.scijava.thread.DefaultThreadService$2.call(DefaultThreadService.java:191)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
-------------
It's possible to start and run the updater manually.

Information about your version of Java:

  os.arch => amd64
  os.name => Windows 7
  os.version => 6.1
  java.version => 1.8.0_51
  java.vendor => Oracle Corporation
  java.runtime.name => Java(TM) SE Runtime Environment
  java.runtime.version => 1.8.0_51-b16
  java.vm.name => Java HotSpot(TM) 64-Bit Server VM
  java.vm.version => 25.51-b03
  java.vm.vendor => Oracle Corporation
  java.vm.info => mixed mode
  java.awt.graphicsenv => sun.awt.Win32GraphicsEnvironment
  java.specification.name => Java Platform API Specification
  java.specification.version => 1.8
  sun.cpu.endian => little
  sun.desktop => windows
  file.separator => \

The up-to-date check says: UP_TO_DATE

Information relevant to JAVA_HOME related problems:

  JAVA_HOME is set to: C:\Program Files\Java\jdk1.8.0_51/jre
  imagej.dir => C:\OPENSP~1\OpenSPIM.app

Information about the version of each plugin:

Activated update sites:
ImageJ: http://update.imagej.net/ (last check:20151222031554)
Fiji: http://update.fiji.sc/ (last check:20151222052403)
OpenSPIM: http://openspim.org/update/ (last check:20151217184431)
Micro-Manager-dev: http://sites.imagej.net/Micro-Manager-dev/ (last check:20160113084010)

Files not up-to-date:
  3cea8b06 (MODIFIED) 20141223094152 mm/win64/PiUsb.dll
  0930b236 (LOCAL_ONLY) 20150715143430 plugins/VSNR2_plugin.jar