In studio, when a guess schema action is executed and failed, the log displayed in very restrictive and does not give many hints to investigate on failure. The execution is made via an external process : Studio >  Guess Schema mock job (external ps) > component-runtime invokes > connector's guess schema code. Here's a sample before change: java.lang.Exception: [FATAL] 10:29:02 local_project.mock_job_for_guess_schema_0_1.Mock_job_for_Guess_schema- tDataPrepRun2_1 There is no available schema found.     at org.talend.sdk.component.studio.ui.guessschema.GuessSchemaSelectionAdapter.widgetSelected(GuessSchemaSelectionAdapter.java:153)     at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:252)     at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89)     at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4209)     at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1043)     at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4026)     at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3626)     at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1157)     at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)     at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1046)     at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:155)     at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:644)     at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)     at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:551)     at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:156)     at org.talend.rcp.intro.Application.start(Application.java:304)     at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:203)     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:401)     at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:255)     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)     at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)     at java.base/java.lang.reflect.Method.invoke(Method.java:566)     at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:654)     at org.eclipse.equinox.launcher.Main.basicRun(Main.java:591)     at org.eclipse.equinox.launcher.Main.run(Main.java:1462) Caused by: java.lang.Exception     at org.talend.sdk.component.studio.ui.guessschema.GuessSchemaSelectionAdapter.widgetSelected(GuessSchemaSelectionAdapter.java:149)     ... 27 more After changes, this is more verbose and informative:  java.lang.Exception: Exception in component tDataPrepRun2_1 (Mock_job_for_Guess_schema) java.lang.Exception: There is no available schema found.     at org.talend.sdk.component.runtime.di.schema.TaCoKitGuessSchema.guessComponentSchema(TaCoKitGuessSchema.java:187)     at local.mock_job_for_guess_schema_0_1.Mock_job_for_Guess_schema.tRowGenerator_1Process(Mock_job_for_Guess_schema.java:881)     at local.mock_job_for_guess_schema_0_1.Mock_job_for_Guess_schema.runJobInTOS(Mock_job_for_Guess_schema.java:1653)     at local.mock_job_for_guess_schema_0_1.Mock_job_for_Guess_schema.main(Mock_job_for_Guess_schema.java:1373) ===== Root cause ====== [ERROR] 17:31:55 org.talend.sdk.component.runtime.di.schema.TaCoKitGuessSchema- Can't guess processor schema through action. java.lang.IllegalStateException: java.net.ConnectException: Connection refused     at org.talend.sdk.component.runtime.manager.service.http.ExecutionContext.apply(ExecutionContext.java:130) ~[component-runtime-manager-1.51.2.jar:?]     at org.talend.sdk.component.runtime.manager.service.http.HttpClientFactoryImpl$HttpHandler.invoke(HttpClientFactoryImpl.java:174) ~[component-runtime-manager-1.51.2.jar:?]     at jdk.proxy3.$Proxy50.newToken(Unknown Source) ~[?:?]     at org.talend.components.dataprep.service.security.SecurityService.findNewToken(SecurityService.java:162) ~[dataprep-1.40.0-SNAPSHOT.jar:?]     at org.talend.components.dataprep.service.security.SecurityService.retrieveNewToken(SecurityService.java:114) ~[dataprep-1.40.0-SNAPSHOT.jar:?]     at org.talend.components.dataprep.service.security.SecurityService.lambda$retrievePreparationTokenManager$2d0af4f$1(SecurityService.java:49) ~[dataprep-1.40.0-SNAPSHOT.jar:?]     at org.talend.components.dataprep.security.TokenManager.getValidToken(TokenManager.java:28) ~[dataprep-1.40.0-SNAPSHOT.jar:?]     at org.talend.components.dataprep.service.DataprepService.newToken(DataprepService.java:253) ~[dataprep-1.40.0-SNAPSHOT.jar:?]     at org.talend.components.dataprep.service.DataprepService.getSchema(DataprepService.java:181) ~[dataprep-1.40.0-SNAPSHOT.jar:?]     at org.talend.components.dataprep.service.DataprepService.guessSchema(DataprepService.java:175) ~[dataprep-1.40.0-SNAPSHOT.jar:?]     at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]     at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[?:?]     at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]     at java.lang.reflect.Method.invoke(Method.java:568) ~[?:?]     at org.talend.sdk.component.runtime.manager.ComponentManager$Updater.lambda$createServiceMeta$35(ComponentManager.java:1467) ~[component-runtime-manager-1.51.2.jar:?]     at org.talend.sdk.component.runtime.manager.ComponentManager.executeInContainer(ComponentManager.java:903) ~[component-runtime-manager-1.51.2.jar:?]     at org.talend.sdk.component.runtime.manager.ComponentManager.access$1500(ComponentManager.java:191) ~[component-runtime-manager-1.51.2.jar:?]     at org.talend.sdk.component.runtime.manager.ComponentManager$Updater.lambda$createServiceMeta$36(ComponentManager.java:1464) ~[component-runtime-manager-1.51.2.jar:?]     at org.talend.sdk.component.runtime.di.schema.TaCoKitGuessSchema.guessComponentSchema(TaCoKitGuessSchema.java:178) [component-runtime-di-1.51.2.jar:?]     at local.mock_job_for_guess_schema_0_1.Mock_job_for_Guess_schema.tRowGenerator_1Process(Mock_job_for_Guess_schema.java:881) [classes/:?]     at local.mock_job_for_guess_schema_0_1.Mock_job_for_Guess_schema.runJobInTOS(Mock_job_for_Guess_schema.java:1653) [classes/:?]     at local.mock_job_for_guess_schema_0_1.Mock_job_for_Guess_schema.main(Mock_job_for_Guess_schema.java:1373) [classes/:?] Caused by: java.net.ConnectException: Connection refused     at sun.nio.ch.Net.connect0(Native Method) ~[?:?]     at sun.nio.ch.Net.connect(Net.java:579) ~[?:?]     at sun.nio.ch.Net.connect(Net.java:568) ~[?:?]     at sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:588) ~[?:?]     at java.net.Socket.connect(Socket.java:633) ~[?:?]     at java.net.Socket.connect(Socket.java:583) ~[?:?]     at sun.net.NetworkClient.doConnect(NetworkClient.java:183) ~[?:?]     at sun.net.www.http.HttpClient.openServer(HttpClient.java:531) ~[?:?]     at sun.net.www.http.HttpClient.openServer(HttpClient.java:636) ~[?:?]     at sun.net.www.http.HttpClient.<init>(HttpClient.java:279) ~[?:?]     at sun.net.www.http.HttpClient.New(HttpClient.java:384) ~[?:?]     at sun.net.www.http.HttpClient.New(HttpClient.java:406) ~[?:?]     at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1309) ~[?:?]     at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1242) ~[?:?]     at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1128) ~[?:?]     at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1057) ~[?:?]     at sun.net.www.protocol.http.HttpURLConnection.getOutputStream0(HttpURLConnection.java:1430) ~[?:?]     at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1401) ~[?:?]     at org.talend.sdk.component.runtime.manager.service.http.ExecutionContext.apply(ExecutionContext.java:80) ~[component-runtime-manager-1.51.2.jar:?]     ... 21 more [ERROR] 17:31:55 org.talend.sdk.component.runtime.di.schema.TaCoKitGuessSchema- Result of built-in guess schema action is not an instance of Talend Component Kit Schema. [FATAL] 17:31:55 local.mock_job_for_guess_schema_0_1.Mock_job_for_Guess_schema- tDataPrepRun2_1 There is no available schema found. java.lang.Exception: There is no available schema found.     at org.talend.sdk.component.runtime.di.schema.TaCoKitGuessSchema.guessComponentSchema(TaCoKitGuessSchema.java:187) ~[component-runtime-di-1.51.2.jar:?]     at local.mock_job_for_guess_schema_0_1.Mock_job_for_Guess_schema.tRowGenerator_1Process(Mock_job_for_Guess_schema.java:881) [classes/:?]     at local.mock_job_for_guess_schema_0_1.Mock_job_for_Guess_schema.runJobInTOS(Mock_job_for_Guess_schema.java:1653) [classes/:?]     at local.mock_job_for_guess_schema_0_1.Mock_job_for_Guess_schema.main(Mock_job_for_Guess_schema.java:1373) [classes/:?]     at org.talend.sdk.component.studio.ui.guessschema.GuessSchemaSelectionAdapter.widgetSelected(GuessSchemaSelectionAdapter.java:153)     at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:252)     at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89)     at org.eclipse.swt.widgets.Display.sendEvent(Display.java:5879)     at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1427)     at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:5121)     at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:4599)     at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1157)     at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)     at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1046)     at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:155)     at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:644)     at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)     at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:551)     at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:156)     at org.talend.rcp.intro.Application.start(Application.java:304)     at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:203)     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:401)     at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:255)     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)     at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)     at java.base/java.lang.reflect.Method.invoke(Method.java:568)     at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:654)     at org.eclipse.equinox.launcher.Main.basicRun(Main.java:591)     at org.eclipse.equinox.launcher.Main.run(Main.java:1462)     at org.eclipse.equinox.launcher.Main.main(Main.java:1435) Caused by: java.lang.Exception     at org.talend.sdk.component.studio.ui.guessschema.GuessSchemaSelectionAdapter.widgetSelected(GuessSchemaSelectionAdapter.java:149)     ... 28 more