Eclipse:An error has occurred. See error log for more details. java.lang.NullPointerException

Problem description
In the use of Eclipse the Clean project times wrong: An error has occurred. See the error log for more details. Java. Lang. NullPointerException . Guess this is due to Eclipse not closing normally.

Open Eclipse log\workspace\.metadata\. Log as follows:

!ENTRY org.eclipse.jface 4 2 2019-04-25 15:42:06.381
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.jface".
!STACK 0
java.lang.NullPointerException
	at org.eclipse.jst.jee.ui.internal.navigator.web.WebAppProvider.getImage(WebAppProvider.java:99)
	at org.eclipse.jst.jee.ui.internal.navigator.Web25LabelProvider.getImage(Web25LabelProvider.java:47)
	at org.eclipse.ui.internal.navigator.NavigatorContentServiceLabelProvider.findImage(NavigatorContentServiceLabelProvider.java:197)
	at org.eclipse.ui.internal.navigator.NavigatorContentServiceLabelProvider.getColumnImage(NavigatorContentServiceLabelProvider.java:105)
	at org.eclipse.ui.internal.navigator.NavigatorContentServiceLabelProvider.getImage(NavigatorContentServiceLabelProvider.java:98)
	at org.eclipse.ui.internal.navigator.NavigatorDecoratingLabelProvider$StyledLabelProviderAdapter.getImage(NavigatorDecoratingLabelProvider.java:59)
	at org.eclipse.jface.viewers.DelegatingStyledCellLabelProvider.getImage(DelegatingStyledCellLabelProvider.java:195)
	at org.eclipse.jface.viewers.DecoratingStyledCellLabelProvider.getImage(DecoratingStyledCellLabelProvider.java:173)
	at org.eclipse.jface.viewers.DelegatingStyledCellLabelProvider.update(DelegatingStyledCellLabelProvider.java:121)
	at org.eclipse.jface.viewers.DecoratingStyledCellLabelProvider.update(DecoratingStyledCellLabelProvider.java:136)
	at org.eclipse.jface.viewers.ViewerColumn.refresh(ViewerColumn.java:154)
	at org.eclipse.jface.viewers.AbstractTreeViewer.doUpdateItem(AbstractTreeViewer.java:949)
	at org.eclipse.jface.viewers.AbstractTreeViewer$UpdateItemSafeRunnable.run(AbstractTreeViewer.java:114)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
	at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:50)
	at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:178)
	at org.eclipse.jface.viewers.AbstractTreeViewer.doUpdateItem(AbstractTreeViewer.java:1029)
	at org.eclipse.jface.viewers.StructuredViewer$UpdateItemSafeRunnable.run(StructuredViewer.java:472)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
	at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:50)
	at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:178)
	at org.eclipse.jface.viewers.StructuredViewer.updateItem(StructuredViewer.java:2150)
	at org.eclipse.jface.viewers.StructuredViewer.internalUpdate(StructuredViewer.java:2133)
	at org.eclipse.jface.viewers.StructuredViewer.update(StructuredViewer.java:2071)
	at org.eclipse.jface.viewers.ColumnViewer.update(ColumnViewer.java:540)
	at org.eclipse.ui.navigator.CommonViewer.update(CommonViewer.java:535)
	at org.eclipse.jface.viewers.StructuredViewer.update(StructuredViewer.java:2015)
	at org.eclipse.jface.viewers.StructuredViewer.handleLabelProviderChanged(StructuredViewer.java:1182)
	at org.eclipse.ui.navigator.CommonViewer.handleLabelProviderChanged(CommonViewer.java:235)
	at org.eclipse.jface.viewers.ContentViewer$1.labelProviderChanged(ContentViewer.java:99)
	at org.eclipse.jface.viewers.BaseLabelProvider$1.run(BaseLabelProvider.java:72)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
	at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:50)
	at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:178)
	at org.eclipse.jface.viewers.BaseLabelProvider.fireLabelProviderChanged(BaseLabelProvider.java:69)
	at org.eclipse.jface.viewers.DecoratingStyledCellLabelProvider$1.labelProviderChanged(DecoratingStyledCellLabelProvider.java:78)
	at org.eclipse.ui.internal.decorators.DecoratorManager$1.run(DecoratorManager.java:446)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
	at org.eclipse.ui.internal.decorators.DecoratorManager.fireListener(DecoratorManager.java:443)
	at org.eclipse.ui.internal.decorators.DecorationScheduler$3.runInUIThread(DecorationScheduler.java:536)
	at org.eclipse.ui.progress.UIJob$1.run(UIJob.java:97)
	at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
	at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:136)
	at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4147)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3764)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1151)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1032)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:148)
	at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:636)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:579)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:150)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:135)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:380)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:235)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:648)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:603)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1465)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1438)

The solution

    Delete the current item, be careful not to check this box: Delete project contents on disk (cannot be undone) re-import the item, project -- > Clean... So just a little bit of engineering will do

Some online methods
Try so start Eclipse from the console/terminal with the -clean option.
On Windows:
Eclipse.exe -clean
On Linux/Unix:
./eclipse -clean
or if Eclipse is in your PATH
eclipse -clean
This will clear your plug-ins cache, maybe it solves the issue.


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