I received an update today for my Eclipse (STS version 3.3.0). The update required eclipse to restart, but Eclipse kept failing to start. After checking the log file mentioned in the error message from GUI, I found this:
!ENTRY org.eclipse.osgi 4 0 2014-04-07 10:31:11.926
!MESSAGE Startup error
!STACK 1
java.lang.RuntimeException: Exception in org.eclipse.osgi.framework.internal.core.SystemBundleActivator.start() of bundle org.eclipse.osgi.
at org.eclipse.osgi.framework.internal.core.InternalSystemBundle.resume(InternalSystemBundle.java:233)
at org.eclipse.osgi.framework.internal.core.Framework.launch(Framework.java:656)
at org.eclipse.core.runtime.adaptor.EclipseStarter.startup(EclipseStarter.java:275)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:177)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:636)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:591)
at org.eclipse.equinox.launcher.Main.run(Main.java:1450)
Caused by: org.osgi.framework.BundleException: Exception in org.eclipse.osgi.framework.internal.core.SystemBundleActivator.start() of bundle org.eclipse.osgi.
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:734)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:683)
at org.eclipse.osgi.framework.internal.core.InternalSystemBundle.resume(InternalSystemBundle.java:225)
... 10 more
Caused by: java.lang.IllegalStateException: The System Bundle could not be resolved: Another singleton version selected: org.eclipse.osgi_3.9.1.v20140110-1610
at org.eclipse.osgi.internal.baseadaptor.BaseStorage.checkSystemState(BaseStorage.java:827)
at org.eclipse.osgi.internal.baseadaptor.BaseStorage.getStateManager(BaseStorage.java:800)
at org.eclipse.osgi.baseadaptor.BaseAdaptor.getState(BaseAdaptor.java:387)
at org.eclipse.osgi.internal.baseadaptor.BaseStorage.frameworkStart(BaseStorage.java:923)
at org.eclipse.osgi.baseadaptor.BaseAdaptor.frameworkStart(BaseAdaptor.java:250)
at org.eclipse.osgi.framework.internal.core.SystemBundleActivator.start(SystemBundleActivator.java:60)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl$1.run(BundleContextImpl.java:711)
at java.security.AccessController.doPrivileged(Native Method)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:702)
... 12 more