diff --git a/idea/resources-en/messages/KotlinBundle.properties b/idea/resources-en/messages/KotlinBundle.properties
index 08af5456657..bfeb8293ca5 100644
--- a/idea/resources-en/messages/KotlinBundle.properties
+++ b/idea/resources-en/messages/KotlinBundle.properties
@@ -738,6 +738,8 @@ configuration.title.outdated.bundled.kotlin.compiler=Outdated Bundled Kotlin Com
 configuration.title.stable=Stable
 configuration.warning.text.following.modules.override.project.settings=Following modules override project settings:
 configuration.warning.text.modules.override.project.settings={0} modules override project settings
+configuration.warning.text.language.version.unsupported=Language version {0} is no longer supported
+configuration.warning.text.api.version.unsupported=API version {0} is no longer supported
 
 #Refactoring
 0.1.is.never.used={0} ''{1}'' is never used
diff --git a/idea/src/org/jetbrains/kotlin/idea/compiler/configuration/KotlinCompilerConfigurableTab.form b/idea/src/org/jetbrains/kotlin/idea/compiler/configuration/KotlinCompilerConfigurableTab.form
index 3cbb19a85f9..9e9e89f373f 100644
--- a/idea/src/org/jetbrains/kotlin/idea/compiler/configuration/KotlinCompilerConfigurableTab.form
+++ b/idea/src/org/jetbrains/kotlin/idea/compiler/configuration/KotlinCompilerConfigurableTab.form
@@ -299,7 +299,7 @@
               <text resource-bundle="messages/KotlinBundle" key="language.version"/>
             </properties>
           </component>
-          <component id="d931b" class="javax.swing.JComboBox" binding="languageVersionComboBox">
+          <component id="d931b" class="javax.swing.JComboBox" binding="languageVersionComboBox" custom-create="true">
             <constraints>
               <grid row="0" column="1" row-span="1" col-span="1" vsize-policy="0" hsize-policy="2" anchor="8" fill="1" indent="0" use-parent-layout="false"/>
             </constraints>
@@ -323,7 +323,7 @@
               <text resource-bundle="messages/KotlinBundle" key="api.version"/>
             </properties>
           </component>
-          <component id="ab3e4" class="javax.swing.JComboBox" binding="apiVersionComboBox">
+          <component id="ab3e4" class="javax.swing.JComboBox" binding="apiVersionComboBox" custom-create="true">
             <constraints>
               <grid row="0" column="1" row-span="1" col-span="1" vsize-policy="0" hsize-policy="2" anchor="8" fill="1" indent="0" use-parent-layout="false"/>
             </constraints>
diff --git a/idea/src/org/jetbrains/kotlin/idea/compiler/configuration/KotlinCompilerConfigurableTab.java b/idea/src/org/jetbrains/kotlin/idea/compiler/configuration/KotlinCompilerConfigurableTab.java
index 05d1d7ffdb5..85eca5f98e3 100644
--- a/idea/src/org/jetbrains/kotlin/idea/compiler/configuration/KotlinCompilerConfigurableTab.java
+++ b/idea/src/org/jetbrains/kotlin/idea/compiler/configuration/KotlinCompilerConfigurableTab.java
@@ -12,8 +12,8 @@ import com.intellij.openapi.module.ModuleManager;
 import com.intellij.openapi.options.ConfigurationException;
 import com.intellij.openapi.options.SearchableConfigurable;
 import com.intellij.openapi.project.Project;
-import com.intellij.openapi.ui.TextComponentAccessor;
-import com.intellij.openapi.ui.TextFieldWithBrowseButton;
+import com.intellij.openapi.ui.*;
+import com.intellij.openapi.util.Disposer;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.ui.ListCellRendererWrapper;
 import com.intellij.ui.RawCommandLineEditor;
@@ -49,6 +49,7 @@ import org.jetbrains.kotlin.platform.jvm.JdkPlatform;
 
 import javax.swing.*;
 import java.util.*;
+import java.util.List;
 
 public class KotlinCompilerConfigurableTab implements SearchableConfigurable {
     private static final Map<String, String> moduleKindDescriptions = new LinkedHashMap<>();
@@ -324,7 +325,8 @@ public class KotlinCompilerConfigurableTab implements SearchableConfigurable {
         return VersionComparatorUtil.compare(version.getVersionString(), upperBound.getVersionString()) <= 0;
     }
 
-    public void onLanguageLevelChanged(VersionView languageLevel) {
+    public void onLanguageLevelChanged(@Nullable VersionView languageLevel) {
+        if (languageLevel == null) return;
         restrictAPIVersions(languageLevel);
         coroutinesPanel.setVisible(languageLevel.getVersion().compareTo(LanguageVersion.KOTLIN_1_3) < 0);
     }
@@ -587,9 +589,9 @@ public class KotlinCompilerConfigurableTab implements SearchableConfigurable {
     @Override
     public void reset() {
         reportWarningsCheckBox.setSelected(!commonCompilerArguments.getSuppressWarnings());
-        languageVersionComboBox.setSelectedItem(KotlinFacetSettingsKt.getLanguageVersionView(commonCompilerArguments));
-        onLanguageLevelChanged(getSelectedLanguageVersionView());
-        apiVersionComboBox.setSelectedItem(KotlinFacetSettingsKt.getApiVersionView(commonCompilerArguments));
+        setSelectedItem(languageVersionComboBox, KotlinFacetSettingsKt.getLanguageVersionView(commonCompilerArguments));
+        onLanguageLevelChanged((VersionView) languageVersionComboBox.getSelectedItem()); // getSelectedLanguageVersionView() replaces null
+        setSelectedItem(apiVersionComboBox, KotlinFacetSettingsKt.getApiVersionView(commonCompilerArguments));
         coroutineSupportComboBox.setSelectedItem(CoroutineSupport.byCompilerArguments(commonCompilerArguments));
         additionalArgsOptionsField.setText(compilerSettings.getAdditionalArguments());
         scriptTemplatesField.setText(compilerSettings.getScriptTemplates());
@@ -615,6 +617,15 @@ public class KotlinCompilerConfigurableTab implements SearchableConfigurable {
         jvmVersionComboBox.setSelectedItem(getJvmVersionOrDefault(k2jvmCompilerArguments.getJvmTarget()));
     }
 
+    private static void setSelectedItem(JComboBox<VersionView> comboBox, VersionView versionView) {
+        // Imported projects might have outdated language/api versions - we display them as well (see createVersionValidator() for details)
+        int index = ((DefaultComboBoxModel<VersionView>) comboBox.getModel()).getIndexOf(versionView);
+        if (index == -1)
+            comboBox.addItem(versionView);
+
+        comboBox.setSelectedItem(versionView);
+    }
+
     @Override
     public void disposeUIResources() {
     }
@@ -729,6 +740,13 @@ public class KotlinCompilerConfigurableTab implements SearchableConfigurable {
     }
 
     private void createUIComponents() {
+        // Explicit use of DefaultComboBoxModel guarantees that setSelectedItem() can make safe cast.
+        languageVersionComboBox = new ComboBox<>(new DefaultComboBoxModel<>());
+        apiVersionComboBox = new ComboBox<>(new DefaultComboBoxModel<>());
+
+        createVersionValidator(languageVersionComboBox, "configuration.warning.text.language.version.unsupported");
+        createVersionValidator(apiVersionComboBox, "configuration.warning.text.api.version.unsupported");
+
         // Workaround: ThreeStateCheckBox doesn't send suitable notification on state change
         // TODO: replace with PropertyChangerListener after fix is available in IDEA
         copyRuntimeFilesCheckBox = new ThreeStateCheckBox() {
@@ -739,4 +757,19 @@ public class KotlinCompilerConfigurableTab implements SearchableConfigurable {
             }
         };
     }
+
+    private static void createVersionValidator(JComboBox<VersionView> component, String messageKey) {
+        new ComponentValidator(Disposer.newDisposable())
+                .withValidator(() -> {
+                    VersionView selectedItem = (VersionView) component.getSelectedItem();
+                    if (selectedItem == null) return null;
+
+                    LanguageVersion version = selectedItem.getVersion();
+                    if (version.isUnsupported())
+                        return new ValidationInfo(KotlinBundle.message(messageKey, version.getVersionString()), component);
+
+                    return null;
+                }).installOn(component);
+        component.addActionListener(e -> ComponentValidator.getInstance(component).ifPresent(ComponentValidator::revalidate));
+    }
 }