Problem arose with update on 2/27. The following exception is thrown when applying a threshold to stacks:

(Fiji Is Just) ImageJ 2.0.0-rc-25/1.49m; Java 1.6.0_65 [64-bit]; Mac OS X 10.10.2; 179MB of 3497MB (5%)
 
java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.NullPointerException
	at net.imagej.legacy.DefaultLegacyService.runLegacyCompatibleCommand(DefaultLegacyService.java:256)
	at net.imagej.legacy.DefaultLegacyHooks.interceptRunPlugIn(DefaultLegacyHooks.java:160)
	at ij.IJ.runPlugIn(IJ.java)
	at ij.Executer.runCommand(Executer.java:131)
	at ij.Executer.run(Executer.java:64)
	at java.lang.Thread.run(Thread.java:695)
Caused by: java.util.concurrent.ExecutionException: java.lang.NullPointerException
	at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:222)
	at java.util.concurrent.FutureTask.get(FutureTask.java:83)
	at net.imagej.legacy.DefaultLegacyService.runLegacyCompatibleCommand(DefaultLegacyService.java:252)
	... 5 more
Caused by: java.lang.NullPointerException
	at net.imagej.legacy.translate.AbstractDisplayCreator.getDataset(AbstractDisplayCreator.java:76)
	at net.imagej.legacy.translate.GrayDisplayCreator.grayCase(GrayDisplayCreator.java:159)
	at net.imagej.legacy.translate.GrayDisplayCreator.makeDisplay(GrayDisplayCreator.java:129)
	at net.imagej.legacy.translate.AbstractDisplayCreator.createDisplay(AbstractDisplayCreator.java:63)
	at net.imagej.legacy.translate.DefaultImageTranslator.createDisplay(DefaultImageTranslator.java:100)
	at net.imagej.legacy.translate.DefaultImageTranslator.createDisplay(DefaultImageTranslator.java:84)
	at net.imagej.legacy.LegacyImageMap.registerLegacyImage(LegacyImageMap.java:271)
	at net.imagej.legacy.display.LegacyImageDisplayService.getActiveImageDisplay(LegacyImageDisplayService.java:119)
	at net.imagej.display.ActiveImagePreprocessor.process(ActiveImagePreprocessor.java:88)
	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$2.call(DefaultThreadService.java:164)
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
	at java.util.concurrent.FutureTask.run(FutureTask.java:138)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
	... 1 more

Information about your version of Java:

  os.arch => x86_64
  os.name => Mac OS X
  os.version => 10.10.2
  java.version => 1.6.0_65
  java.vendor => Apple Inc.
  java.runtime.name => Java(TM) SE Runtime Environment
  java.runtime.version => 1.6.0_65-b14-466.1-11M4716
  java.vm.name => Java HotSpot(TM) 64-Bit Server VM
  java.vm.version => 20.65-b04-466.1
  java.vm.vendor => Apple Inc.
  java.vm.info => mixed mode
  java.awt.graphicsenv => apple.awt.CGraphicsEnvironment
  java.specification.name => Java Platform API Specification
  java.specification.version => 1.6
  sun.cpu.endian => little
  sun.desktop => null
  file.separator => /

The up-to-date check says: UPDATEABLE

Information relevant to JAVA_HOME related problems:

  JAVA_HOME is set to: null
  imagej.dir => /Applications/Fiji.app

Information about the version of each plugin:

Activated update sites:
ImageJ: http://update.imagej.net/ (last check:20150226143217)
Fiji: http://fiji.sc/update/ (last check:20150226143401)

Files not up-to-date:
  1ad3be0d (LOCAL_ONLY) 20140925112353 jars/jpedalSTD.jar