Could not load codec 'Lucene99' (again)

[gnl42]

Suddenly seeing this one again (#492). Cleared up after I restart Eclipse
It's happened twice to me so far (different workspaces):

java.lang.IllegalArgumentException: Could not load codec 'Lucene99'. Did you forget to add lucene-backward-codecs.jar? at org.apache.lucene.index.SegmentInfos.readCodec(SegmentInfos.java:521) at org.apache.lucene.index.SegmentInfos.parseSegmentInfos(SegmentInfos.java:410) at org.apache.lucene.index.SegmentInfos.readCommit(SegmentInfos.java:369) at org.apache.lucene.index.SegmentInfos.readCommit(SegmentInfos.java:305) at org.apache.lucene.index.StandardDirectoryReader$1.doBody(StandardDirectoryReader.java:88) at org.apache.lucene.index.StandardDirectoryReader$1.doBody(StandardDirectoryReader.java:77) at org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:821) at org.apache.lucene.index.StandardDirectoryReader.open(StandardDirectoryReader.java:109) at org.apache.lucene.index.StandardDirectoryReader.open(StandardDirectoryReader.java:67) at org.apache.lucene.index.DirectoryReader.open(DirectoryReader.java:60) at org.eclipse.mylyn.internal.tasks.index.core.TaskListIndex.getIndexReader(TaskListIndex.java:787) at org.eclipse.mylyn.internal.tasks.index.core.TaskListIndex.matches(TaskListIndex.java:583) at org.eclipse.mylyn.internal.tasks.index.ui.IndexedSubstringPatternFilter.isLeafMatch(IndexedSubstringPatternFilter.java:48) at org.eclipse.ui.dialogs.PatternFilter.isElementVisible(PatternFilter.java:230) at org.eclipse.ui.dialogs.PatternFilter.computeAnyVisible(PatternFilter.java:131) at org.eclipse.ui.dialogs.PatternFilter.isAnyVisible(PatternFilter.java:114) at org.eclipse.ui.dialogs.PatternFilter.isParentMatch(PatternFilter.java:250) at org.eclipse.ui.dialogs.PatternFilter.isElementVisible(PatternFilter.java:230) at org.eclipse.ui.dialogs.PatternFilter.select(PatternFilter.java:138) at org.eclipse.jface.viewers.ViewerFilter.filter(ViewerFilter.java:62) at org.eclipse.ui.dialogs.PatternFilter.filter(PatternFilter.java:85) at org.eclipse.jface.viewers.StructuredViewer.getFilteredChildren(StructuredViewer.java:855) at org.eclipse.jface.viewers.StructuredViewer.getSortedChildren(StructuredViewer.java:1025) at org.eclipse.jface.viewers.ColumnViewer.getSortedChildren(ColumnViewer.java:821) at org.eclipse.jface.viewers.AbstractTreeViewer.getSortedChildren(AbstractTreeViewer.java:690) at org.eclipse.jface.viewers.AbstractTreeViewer.updateChildren(AbstractTreeViewer.java:2896) at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefreshStruct(AbstractTreeViewer.java:2031) at org.eclipse.jface.viewers.TreeViewer.internalRefreshStruct(TreeViewer.java:684) at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefresh(AbstractTreeViewer.java:2004) at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefresh(AbstractTreeViewer.java:1961) at org.eclipse.jface.viewers.StructuredViewer.lambda$3(StructuredViewer.java:1486) at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1392) at org.eclipse.jface.viewers.TreeViewer.preservingSelection(TreeViewer.java:367) at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1353) at org.eclipse.jface.viewers.StructuredViewer.refresh(StructuredViewer.java:1486) at org.eclipse.jface.viewers.ColumnViewer.refresh(ColumnViewer.java:533) at org.eclipse.ui.dialogs.FilteredTree$NotifyingTreeViewer.refresh(FilteredTree.java:1008) at org.eclipse.jface.viewers.StructuredViewer.refresh(StructuredViewer.java:1447) at org.eclipse.ui.dialogs.FilteredTree$NotifyingTreeViewer.refresh(FilteredTree.java:996) at org.eclipse.ui.dialogs.FilteredTree$1.runInUIThread(FilteredTree.java:516) at org.eclipse.ui.progress.UIJob.lambda$0(UIJob.java:148) at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:40) at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:132) at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4141) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3757) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1151) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1042) at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:153) at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:663) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:570) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:173) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:178) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:208) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:143) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:109) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:439) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:271) at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103) at java.base/java.lang.reflect.Method.invoke(Method.java:580) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:668) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:605) at org.eclipse.equinox.launcher.Main.run(Main.java:1481) Suppressed: org.apache.lucene.index.CorruptIndexException: checksum passed (8f75448f). possibly transient resource issue, or a Lucene or JVM bug (resource=BufferedChecksumIndexInput(NIOFSIndexInput(path="E:\workspaces\mylyn-main\ws\.metadata\.mylyn\.taskListIndex\segments_1d"))) at org.apache.lucene.codecs.CodecUtil.checkFooter(CodecUtil.java:501) at org.apache.lucene.index.SegmentInfos.readCommit(SegmentInfos.java:376) ... 61 more Caused by: java.lang.IllegalArgumentException: An SPI class of type org.apache.lucene.codecs.Codec with name 'Lucene99' does not exist. You need to add the corresponding JAR file supporting this SPI to your classpath. The current classpath supports the following names: [Lucene912] at org.apache.lucene.util.NamedSPILoader.lookup(NamedSPILoader.java:113) at org.apache.lucene.codecs.Codec.forName(Codec.java:118) at org.apache.lucene.index.SegmentInfos.readCodec(SegmentInfos.java:517) ... 63 more

[ruspl-afed]

Hello @gnl42
We need test data to turn this from magic to engineering. Perhaps you have some indexed data in your workspace encoded with Lucene99