Error while checking server availability. java.io.IOException: Unable to tunnel through proxy. Proxy returns "HTTP/1.1 407 authenticationrequired" at java.base/sun.net.www.protocol.http.HttpURLConnection.doTunneling(HttpURLConnection.java:2168) at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:183) at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(HttpsURLConnectionImpl.java:168) at com.homework.plugin.client.HttpsURLConnectionClient.getServerAvailabilityStatus(HttpsURLConnectionClient.java:714) at com.homework.plugin.button.AbstractButton.isServerAvailable(AbstractButton.java:71) at com.homework.plugin.button.SelectTaskButton.actionPerformed(SelectTaskButton.java:18) at com.intellij.openapi.actionSystem.ex.ActionUtil$1.run(ActionUtil.java:265) at com.intellij.openapi.actionSystem.ex.ActionUtil.performActionDumbAware(ActionUtil.java:282) at com.intellij.openapi.actionSystem.ex.ActionUtil.performActionDumbAwareWithCallbacks(ActionUtil.java:256) at com.intellij.openapi.actionSystem.impl.ActionButton.actionPerformed(ActionButton.java:194) at com.intellij.openapi.actionSystem.impl.ActionButton.performAction(ActionButton.java:157) at com.intellij.openapi.actionSystem.impl.ActionButton.processMouseEvent(ActionButton.java:434) at java.desktop/java.awt.Component.processEvent(Component.java:6416) at java.desktop/java.awt.Container.processEvent(Container.java:2263) at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5026) at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321) at java.desktop/java.awt.Component.dispatchEvent(Component.java:4858) at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4918) at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4547) at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4488) at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2307) at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2773) at java.desktop/java.awt.Component.dispatchEvent(Component.java:4858) at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:778) at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:727) at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721) at java.base/java.security.AccessController.doPrivileged(Native Method) at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85) at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95) at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:751) at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:749) at java.base/java.security.AccessController.doPrivileged(Native Method) at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85) at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:748) at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:878) at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:823) at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$8(IdeEventQueue.java:466) at com.intellij.openapi.progress.impl.CoreProgressManager.computePrioritized(CoreProgressManager.java:704) at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:465) at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203) at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124) at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113) at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109) at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)