title: Eclipse won't start, log error says: ObjectNotFoundException: Tree element
body: <p>Last night my machine restarted while Eclipse Galileo was open.  No big deal, right?</p>
  
  <p>This morning, I started my machine and tried to open Eclipse.  Instead of opening, I see this:
  <img src="https://i.stack.imgur.com/kNADb.jpg" alt="alt text"></p>
  
  <p>The error log suggests that there is some kind of problem caused by exiting with unsaved changes.</p>
  
  <p>How can I get Eclipse to open and ignore those unsaved changes?  I can't even open a text file that is not part of this project with Eclipse?  There must be a way to reset this state.</p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>I have tracked down the problem to a single file.  When I delete this file below, Eclipse opens but my projects are missing.</p>
  
  <pre><code>.metadata\.plugins\org.eclipse.core.resources\.snap
  </code></pre>
  
  <p>I do use the subversion plugin, but I don't think that is the problem.  Here is what the error log says ( abbreviated ):</p>
  
  <pre><code>!SESSION 2010-08-17 10:13:01.718 -----------------------------------------------
  eclipse.buildId=M20100211-1343
  java.version=1.4.2_06
  java.vendor=Sun Microsystems Inc.
  BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=en_CA
  Command-line arguments:  -os win32 -ws win32 -arch x86
  
  !ENTRY org.eclipse.core.resources 2 10035 2010-08-17 10:13:02.656
  !MESSAGE The workspace exited with unsaved changes in the previous session; refreshing workspace to recover changes.
  
  !ENTRY org.eclipse.osgi 4 0 2010-08-17 10:13:02.671
  !MESSAGE An error occurred while automatically activating bundle org.eclipse.core.resources (33).
  !STACK 0
  org.osgi.framework.BundleException: Exception in org.eclipse.core.resources.ResourcesPlugin.start() of bundle org.eclipse.core.resources.
      at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:806)
      at org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:755)
  ...
  
  Caused by: org.eclipse.core.internal.dtree.ObjectNotFoundException: Tree element '/reports/src/com/lang/reports/OnlineReport.java' not found.
      at org.eclipse.core.internal.dtree.AbstractDataTree.handleNotFound(AbstractDataTree.java:257)
  ...
  
  Root exception:
  org.eclipse.core.internal.dtree.ObjectNotFoundException: Tree element '/reports/src/com/lang/reports/OnlineReport.java' not found.
      at org.eclipse.core.internal.dtree.AbstractDataTree.handleNotFound(AbstractDataTree.java:257)
  ...
  
  !ENTRY org.eclipse.osgi 4 0 2010-08-17 10:13:02.703
  !MESSAGE Application error
  !STACK 1
  java.lang.NoClassDefFoundError: org/eclipse/core/resources/IContainer
      at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:114)
      at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194)
  
  !ENTRY org.eclipse.osgi 2 0 2010-08-17 10:13:02.765
  !MESSAGE The following is a complete list of bundles which are not resolved, see the prior log entry for the root cause if it exists:
  !SUBENTRY 1 org.eclipse.osgi 2 0 2010-08-17 10:13:02.765
  !MESSAGE Bundle org.eclipse.jdt.apt.core_3.3.202.R35x_v20091130-2300 [103] was not resolved.
  !SUBENTRY 1 org.eclipse.osgi 2 0 2010-08-17 10:13:02.765
  !MESSAGE Bundle org.eclipse.jdt.apt.pluggable.core_1.0.201.R35x_v20090925-1100 [104] was not resolved.
  !SUBENTRY 2 org.eclipse.jdt.apt.pluggable.core 2 0 2010-08-17 10:13:02.765
  !MESSAGE Missing required bundle org.eclipse.jdt.apt.core_0.0.0.
  !SUBENTRY 2 org.eclipse.jdt.apt.pluggable.core 2 0 2010-08-17 10:13:02.765
  !MESSAGE Missing imported package org.eclipse.jdt.internal.compiler.tool_0.0.0.
  !SUBENTRY 2 org.eclipse.jdt.apt.pluggable.core 2 0 2010-08-17 10:13:02.765
  !MESSAGE Missing imported package org.eclipse.jdt.internal.compiler.apt.dispatch_0.0.0.
  !SUBENTRY 2 org.eclipse.jdt.apt.pluggable.core 2 0 2010-08-17 10:13:02.765
  !MESSAGE Missing imported package org.eclipse.jdt.internal.compiler.apt.model_0.0.0.
  !SUBENTRY 2 org.eclipse.jdt.apt.pluggable.core 2 0 2010-08-17 10:13:02.765
  !MESSAGE Missing imported package org.eclipse.jdt.internal.compiler.apt.util_0.0.0.
  !SUBENTRY 1 org.eclipse.osgi 2 0 2010-08-17 10:13:02.765
  !MESSAGE Bundle org.eclipse.jdt.apt.ui_3.3.200.v20090930-2100_R35x [105] was not resolved.
  !SUBENTRY 2 org.eclipse.jdt.apt.ui 2 0 2010-08-17 10:13:02.765
  !MESSAGE Missing required bundle org.eclipse.jdt.apt.core_[3.2.0,4.0.0).
  !SUBENTRY 1 org.eclipse.osgi 2 0 2010-08-17 10:13:02.765
  !MESSAGE Bundle org.eclipse.jdt.compiler.apt_1.0.201.R35x_v20090925-1100 [106] was not resolved.
  !SUBENTRY 2 org.eclipse.jdt.compiler.apt 2 0 2010-08-17 10:13:02.765
  !MESSAGE Missing imported package org.eclipse.jdt.internal.compiler.tool_0.0.0.
  !SUBENTRY 1 org.eclipse.osgi 2 0 2010-08-17 10:13:02.765
  !MESSAGE Bundle org.eclipse.jdt.compiler.tool_1.0.100.v_981_R35x [107] was not resolved.
  !SUBENTRY 1 org.eclipse.osgi 2 0 2010-08-17 10:13:02.765
  !MESSAGE Bundle org.eclipse.jdt.junit4.runtime_1.1.0.v20090513-2000 [116] was not resolved.
  !SUBENTRY 2 org.eclipse.jdt.junit4.runtime 2 0 2010-08-17 10:13:02.765
  !MESSAGE Missing required bundle org.junit4_[4.4.0,5.0.0).
  !SUBENTRY 1 org.eclipse.osgi 2 0 2010-08-17 10:13:02.765
  !MESSAGE Bundle org.hamcrest.core_1.1.0.v20090501071000 [184] was not resolved.
  !SUBENTRY 1 org.eclipse.osgi 2 0 2010-08-17 10:13:02.765
  !MESSAGE Bundle org.junit4_4.5.0.v20090824 [186] was not resolved.
  !SUBENTRY 2 org.junit4 2 0 2010-08-17 10:13:02.765
  !MESSAGE Missing required bundle org.hamcrest.core_1.1.0.
  !SUBENTRY 1 org.eclipse.osgi 2 0 2010-08-17 10:13:02.765
  !MESSAGE Bundle com.collabnet.subversion.merge_2.1.0 [208] was not resolved.
  </code></pre>