Hy all,
i currently noticed, while I was connected to my openHAB instance and editing some configuration file, these error messages popped up in the VS Code window.
I appreciate any help to fix this problem! Thank you in advance 
I noticed this behaviour ocours after several minutes after the openHAB VS Code extension is started. Could it be, that too many items state updates are polled by the openHAB VS Code extension?
VS Code window:
openHAB vscode extension has been activated
[Error - 5:26:12 PM] Request textDocument/definition failed.
Message: Internal error.
Code: -32603
java.util.concurrent.CompletionException: java.lang.RuntimeException: Cannot create a resource for 'java:/Objects/java.lang.Enum'; a registered resource factory is needed
at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:331)
at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:346)
at java.base/java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:704)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2088)
at org.eclipse.xtext.ide.server.concurrent.AbstractRequest.logAndCompleteExceptionally(AbstractRequest.java:73)
at org.eclipse.xtext.ide.server.concurrent.ReadRequest.lambda$doRun$0(ReadRequest.java:69)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.RuntimeException: Cannot create a resource for 'java:/Objects/java.lang.Enum'; a registered resource factory is needed
at org.eclipse.xtext.resource.XtextResourceSet.getResource(XtextResourceSet.java:263)
at org.eclipse.xtext.ide.server.ProjectManager.getResource(ProjectManager.java:169)
at org.eclipse.xtext.ide.server.WorkspaceManager.doRead(WorkspaceManager.java:436)
at org.eclipse.xtext.ide.server.findReferences.WorkspaceResourceAccess.readOnly(WorkspaceResourceAccess.java:36)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.doRead(DocumentSymbolService.java:332)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.getDefinitions(DocumentSymbolService.java:112)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.getDefinitions(DocumentSymbolService.java:99)
at org.eclipse.xtext.ide.server.LanguageServerImpl.lambda$definition$24(LanguageServerImpl.java:603)
at org.eclipse.xtext.ide.server.WorkspaceManager.doRead(WorkspaceManager.java:438)
at org.eclipse.xtext.ide.server.LanguageServerImpl.definition(LanguageServerImpl.java:602)
at org.eclipse.xtext.ide.server.LanguageServerImpl.definition(LanguageServerImpl.java:590)
at org.eclipse.xtext.ide.server.LanguageServerImpl.lambda$definition$23(LanguageServerImpl.java:581)
at org.eclipse.xtext.ide.server.concurrent.ReadRequest.lambda$doRun$0(ReadRequest.java:66)
... 5 more
[Error - 5:26:12 PM] Request textDocument/definition failed.
Message: Internal error.
Code: -32603
java.util.concurrent.CompletionException: java.lang.RuntimeException: Cannot create a resource for 'java:/Objects/java.lang.Enum'; a registered resource factory is needed
at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:331)
at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:346)
at java.base/java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:704)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2088)
at org.eclipse.xtext.ide.server.concurrent.AbstractRequest.logAndCompleteExceptionally(AbstractRequest.java:73)
at org.eclipse.xtext.ide.server.concurrent.ReadRequest.lambda$doRun$0(ReadRequest.java:69)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.RuntimeException: Cannot create a resource for 'java:/Objects/java.lang.Enum'; a registered resource factory is needed
at org.eclipse.xtext.resource.XtextResourceSet.getResource(XtextResourceSet.java:263)
at org.eclipse.xtext.ide.server.ProjectManager.getResource(ProjectManager.java:169)
at org.eclipse.xtext.ide.server.WorkspaceManager.doRead(WorkspaceManager.java:436)
at org.eclipse.xtext.ide.server.findReferences.WorkspaceResourceAccess.readOnly(WorkspaceResourceAccess.java:36)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.doRead(DocumentSymbolService.java:332)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.getDefinitions(DocumentSymbolService.java:112)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.getDefinitions(DocumentSymbolService.java:99)
at org.eclipse.xtext.ide.server.LanguageServerImpl.lambda$definition$24(LanguageServerImpl.java:603)
at org.eclipse.xtext.ide.server.WorkspaceManager.doRead(WorkspaceManager.java:438)
at org.eclipse.xtext.ide.server.LanguageServerImpl.definition(LanguageServerImpl.java:602)
at org.eclipse.xtext.ide.server.LanguageServerImpl.definition(LanguageServerImpl.java:590)
at org.eclipse.xtext.ide.server.LanguageServerImpl.lambda$definition$23(LanguageServerImpl.java:581)
at org.eclipse.xtext.ide.server.concurrent.ReadRequest.lambda$doRun$0(ReadRequest.java:66)
... 5 more
[Error - 5:26:36 PM] Request textDocument/definition failed.
Message: Internal error.
Code: -32603
java.util.concurrent.CompletionException: java.lang.RuntimeException: Cannot create a resource for 'java:/Objects/java.lang.Enum'; a registered resource factory is needed
at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:331)
at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:346)
at java.base/java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:704)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2088)
at org.eclipse.xtext.ide.server.concurrent.AbstractRequest.logAndCompleteExceptionally(AbstractRequest.java:73)
at org.eclipse.xtext.ide.server.concurrent.ReadRequest.lambda$doRun$0(ReadRequest.java:69)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.RuntimeException: Cannot create a resource for 'java:/Objects/java.lang.Enum'; a registered resource factory is needed
at org.eclipse.xtext.resource.XtextResourceSet.getResource(XtextResourceSet.java:263)
at org.eclipse.xtext.ide.server.ProjectManager.getResource(ProjectManager.java:169)
at org.eclipse.xtext.ide.server.WorkspaceManager.doRead(WorkspaceManager.java:436)
at org.eclipse.xtext.ide.server.findReferences.WorkspaceResourceAccess.readOnly(WorkspaceResourceAccess.java:36)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.doRead(DocumentSymbolService.java:332)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.getDefinitions(DocumentSymbolService.java:112)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.getDefinitions(DocumentSymbolService.java:99)
at org.eclipse.xtext.ide.server.LanguageServerImpl.lambda$definition$24(LanguageServerImpl.java:603)
at org.eclipse.xtext.ide.server.WorkspaceManager.doRead(WorkspaceManager.java:438)
at org.eclipse.xtext.ide.server.LanguageServerImpl.definition(LanguageServerImpl.java:602)
at org.eclipse.xtext.ide.server.LanguageServerImpl.definition(LanguageServerImpl.java:590)
at org.eclipse.xtext.ide.server.LanguageServerImpl.lambda$definition$23(LanguageServerImpl.java:581)
at org.eclipse.xtext.ide.server.concurrent.ReadRequest.lambda$doRun$0(ReadRequest.java:66)
... 5 more
[Error - 5:26:38 PM] Request textDocument/definition failed.
Message: Internal error.
Code: -32603
java.util.concurrent.CompletionException: java.lang.RuntimeException: Cannot create a resource for 'java:/Objects/java.lang.Enum'; a registered resource factory is needed
at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:331)
at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:346)
at java.base/java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:704)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2088)
at org.eclipse.xtext.ide.server.concurrent.AbstractRequest.logAndCompleteExceptionally(AbstractRequest.java:73)
at org.eclipse.xtext.ide.server.concurrent.ReadRequest.lambda$doRun$0(ReadRequest.java:69)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.RuntimeException: Cannot create a resource for 'java:/Objects/java.lang.Enum'; a registered resource factory is needed
at org.eclipse.xtext.resource.XtextResourceSet.getResource(XtextResourceSet.java:263)
at org.eclipse.xtext.ide.server.ProjectManager.getResource(ProjectManager.java:169)
at org.eclipse.xtext.ide.server.WorkspaceManager.doRead(WorkspaceManager.java:436)
at org.eclipse.xtext.ide.server.findReferences.WorkspaceResourceAccess.readOnly(WorkspaceResourceAccess.java:36)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.doRead(DocumentSymbolService.java:332)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.getDefinitions(DocumentSymbolService.java:112)
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.getDefinitions(DocumentSymbolService.java:99)
at org.eclipse.xtext.ide.server.LanguageServerImpl.lambda$definition$24(LanguageServerImpl.java:603)
at org.eclipse.xtext.ide.server.WorkspaceManager.doRead(WorkspaceManager.java:438)
at org.eclipse.xtext.ide.server.LanguageServerImpl.definition(LanguageServerImpl.java:602)
at org.eclipse.xtext.ide.server.LanguageServerImpl.definition(LanguageServerImpl.java:590)
at org.eclipse.xtext.ide.server.LanguageServerImpl.lambda$definition$23(LanguageServerImpl.java:581)
at org.eclipse.xtext.ide.server.concurrent.ReadRequest.lambda$doRun$0(ReadRequest.java:66)
... 5 more
openHAB log file
2021-06-23 17:26:39.052 [ERROR] [t.ide.server.concurrent.WriteRequest] - Error during request:
java.util.concurrent.CompletionException: java.lang.RuntimeException: Cannot create a resource for 'java:/Objects/java.lang.Enum'; a registered resource factory is needed
at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:331) ~[?:?]
at java.util.concurrent.CompletableFuture.andTree(CompletableFuture.java:1452) ~[?:?]
at java.util.concurrent.CompletableFuture.andTree(CompletableFuture.java:1442) ~[?:?]
at java.util.concurrent.CompletableFuture.andTree(CompletableFuture.java:1442) ~[?:?]
at java.util.concurrent.CompletableFuture.allOf(CompletableFuture.java:2337) ~[?:?]
at org.eclipse.xtext.ide.server.concurrent.RequestManager.cancel(RequestManager.java:114) ~[?:?]
at org.eclipse.xtext.ide.server.concurrent.RequestManager.runWrite(RequestManager.java:80) ~[?:?]
at org.eclipse.xtext.ide.server.LanguageServerImpl.runBuildable(LanguageServerImpl.java:453) ~[?:?]
at org.eclipse.xtext.ide.server.LanguageServerImpl.didChange(LanguageServerImpl.java:393) ~[?:?]
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?]
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:566) ~[?:?]
at org.eclipse.lsp4j.jsonrpc.services.GenericEndpoint.lambda$null$0(GenericEndpoint.java:65) ~[?:?]
at org.eclipse.lsp4j.jsonrpc.services.GenericEndpoint.notify(GenericEndpoint.java:152) ~[?:?]
at org.eclipse.lsp4j.jsonrpc.RemoteEndpoint.handleNotification(RemoteEndpoint.java:220) ~[?:?]
at org.eclipse.lsp4j.jsonrpc.RemoteEndpoint.consume(RemoteEndpoint.java:187) ~[?:?]
at org.eclipse.lsp4j.jsonrpc.json.StreamMessageProducer.handleMessage(StreamMessageProducer.java:194) ~[?:?]
at org.eclipse.lsp4j.jsonrpc.json.StreamMessageProducer.listen(StreamMessageProducer.java:94) ~[?:?]
at org.eclipse.lsp4j.jsonrpc.json.ConcurrentMessageProcessor.run(ConcurrentMessageProcessor.java:113) ~[?:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) [?:?]
at java.util.concurrent.FutureTask.run(FutureTask.java:264) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
at java.lang.Thread.run(Thread.java:834) [?:?]
Caused by: java.lang.RuntimeException: Cannot create a resource for 'java:/Objects/java.lang.Enum'; a registered resource factory is needed
at org.eclipse.xtext.resource.XtextResourceSet.getResource(XtextResourceSet.java:263) ~[?:?]
at org.eclipse.xtext.ide.server.ProjectManager.getResource(ProjectManager.java:169) ~[?:?]
at org.eclipse.xtext.ide.server.WorkspaceManager.doRead(WorkspaceManager.java:436) ~[?:?]
at org.eclipse.xtext.ide.server.findReferences.WorkspaceResourceAccess.readOnly(WorkspaceResourceAccess.java:36) ~[?:?]
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.doRead(DocumentSymbolService.java:332) ~[?:?]
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.getDefinitions(DocumentSymbolService.java:112) ~[?:?]
at org.eclipse.xtext.ide.server.symbol.DocumentSymbolService.getDefinitions(DocumentSymbolService.java:99) ~[?:?]
at org.eclipse.xtext.ide.server.LanguageServerImpl.lambda$definition$24(LanguageServerImpl.java:603) ~[?:?]
at org.eclipse.xtext.ide.server.WorkspaceManager.doRead(WorkspaceManager.java:438) ~[?:?]
at org.eclipse.xtext.ide.server.LanguageServerImpl.definition(LanguageServerImpl.java:602) ~[?:?]
at org.eclipse.xtext.ide.server.LanguageServerImpl.definition(LanguageServerImpl.java:590) ~[?:?]
at org.eclipse.xtext.ide.server.LanguageServerImpl.lambda$definition$23(LanguageServerImpl.java:581) ~[?:?]
at org.eclipse.xtext.ide.server.concurrent.ReadRequest.lambda$doRun$0(ReadRequest.java:66) ~[?:?]
... 5 more