IDEA Failed to save Settings. Please restart IntelliJ IDEA
said the solution is to uninstall a “identifier Highlighter” plug-in, but my IDEA does not have this plug-in.
after Google finally found a solution.

solution

first make sure you have read/write access to the config file

if the permissions are okay and the error is still reported, move on to the next step.

view log file

find the cause of the error, which may vary from person to person. Therefore, the solution is different.

2017-11-15 17:20:55,720 [ 196716]   WARN - mponents.impl.stores.StoreUtil - Save settings failed 
java.lang.RuntimeException: java.lang.Exception: Cannot get RunManager component state
    at com.intellij.util.ExceptionUtil.rethrow(ExceptionUtil.java:179)
    at com.intellij.util.lang.CompoundRuntimeException.throwIfNotEmpty(CompoundRuntimeException.java:148)
    at com.intellij.configurationStore.ComponentStoreImpl.save(ComponentStoreImpl.kt:199)
    at com.intellij.openapi.components.impl.stores.StoreUtil.save(StoreUtil.java:49)
    at com.intellij.openapi.project.impl.ProjectImpl.save(ProjectImpl.java:349)
    at com.intellij.openapi.components.impl.stores.StoreUtil.saveDocumentsAndProjectsAndApp(StoreUtil.java:126)
    at com.intellij.openapi.application.impl.ApplicationImpl.saveAll(ApplicationImpl.java:1437)
    at com.intellij.ide.SaveAndSyncHandlerImpl.saveProjectsAndDocuments(SaveAndSyncHandlerImpl.java:126)
    at com.intellij.ide.SaveAndSyncHandlerImpl$2.a(SaveAndSyncHandlerImpl.java:94)
    at com.intellij.openapi.application.TransactionGuardImpl.a(TransactionGuardImpl.java:86)
    at com.intellij.openapi.application.TransactionGuardImpl.a(TransactionGuardImpl.java:109)
    at com.intellij.openapi.application.TransactionGuardImpl.submitTransaction(TransactionGuardImpl.java:118)
    at com.intellij.openapi.application.TransactionGuard.submitTransaction(TransactionGuard.java:122)
    at com.intellij.ide.SaveAndSyncHandlerImpl$2.onFrameDeactivated(SaveAndSyncHandlerImpl.java:92)
    at com.intellij.ide.FrameStateManagerImpl.a(FrameStateManagerImpl.java:84)
    at com.intellij.ide.FrameStateManagerImpl.access$500(FrameStateManagerImpl.java:32)
    at com.intellij.ide.FrameStateManagerImpl$2.a(FrameStateManagerImpl.java:70)
    at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:246)
    at com.intellij.util.Alarm$Request.runSafely(Alarm.java:417)
    at com.intellij.util.Alarm$Request.access$700(Alarm.java:344)
    at com.intellij.util.Alarm$Request$1.run(Alarm.java:384)
    at com.intellij.openapi.application.TransactionGuardImpl$2.run(TransactionGuardImpl.java:314)
    at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.a(LaterInvocator.java:416)
    at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:399)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:762)
    at java.awt.EventQueue.access$500(EventQueue.java:98)
    at java.awt.EventQueue$3.run(EventQueue.java:715)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:732)
    at com.intellij.ide.IdeEventQueue.c(IdeEventQueue.java:821)
    at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:649)
    at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:365)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Caused by: java.lang.Exception: Cannot get RunManager component state
    at com.intellij.configurationStore.ComponentStoreImpl.save(ComponentStoreImpl.kt:166)
    ... 38 more
Caused by: java.lang.RuntimeException: Cannot save scheme workspace/Jetty Server: jetty (level: WORKSPACE)
    at com.intellij.configurationStore.SchemeManagerImpl.save(SchemeManagerImpl.kt:535)
    at com.intellij.configurationStore.Scheme_implKt.save(scheme-impl.kt:154)
    at com.intellij.execution.impl.RunManagerImpl.getState(RunManagerImpl.kt:500)
    at com.intellij.execution.impl.RunManagerImpl.getState(RunManagerImpl.kt:63)
    at com.intellij.configurationStore.ComponentStoreImpl.a(ComponentStoreImpl.kt:227)
    at com.intellij.configurationStore.ComponentStoreImpl.save(ComponentStoreImpl.kt:159)
    ... 38 more

I found this sentence:

under Caused by: Java. Lang. RuntimeException: always save scheme workspace/Jetty Server: Jetty (level: workspace)