diff --git a/js/js.translator/src/org/jetbrains/k2js/facade/K2JSTranslator.java b/js/js.translator/src/org/jetbrains/k2js/facade/K2JSTranslator.java
index ee45d570f61..d7cf7ac9c31 100644
--- a/js/js.translator/src/org/jetbrains/k2js/facade/K2JSTranslator.java
+++ b/js/js.translator/src/org/jetbrains/k2js/facade/K2JSTranslator.java
@@ -26,6 +26,7 @@ import org.jetbrains.jet.lang.resolve.BindingContext;
 import org.jetbrains.jet.lang.types.lang.JetStandardLibrary;
 import org.jetbrains.k2js.analyze.AnalyzerFacadeForJS;
 import org.jetbrains.k2js.config.Config;
+import org.jetbrains.k2js.facade.exceptions.TranslationException;
 import org.jetbrains.k2js.generate.CodeGenerator;
 import org.jetbrains.k2js.translate.general.Translation;
 import org.jetbrains.k2js.utils.JetFileUtils;
@@ -75,7 +76,7 @@ public final class K2JSTranslator {
     //TODO: web demo related method
     @SuppressWarnings("UnusedDeclaration")
     @NotNull
-    public String translateStringWithCallToMain(@NotNull String programText, @NotNull String argumentsString) {
+    public String translateStringWithCallToMain(@NotNull String programText, @NotNull String argumentsString) throws TranslationException {
         JetFile file = JetFileUtils.createPsiFile("test", programText, getProject());
         String programCode = generateProgramCode(file, MainCallParameters.mainWithArguments(parseString(argumentsString))) + "\n";
         String flushOutput = "Kotlin.System.flush();\n";
@@ -84,21 +85,23 @@ public final class K2JSTranslator {
     }
 
     @NotNull
-    public String generateProgramCode(@NotNull JetFile file, @NotNull MainCallParameters mainCallParameters) {
+    public String generateProgramCode(@NotNull JetFile file, @NotNull MainCallParameters mainCallParameters) throws TranslationException {
         JsProgram program = generateProgram(Arrays.asList(file), mainCallParameters);
         CodeGenerator generator = new CodeGenerator();
         return generator.generateToString(program);
     }
 
     @NotNull
-    public String generateProgramCode(@NotNull List<JetFile> files, @NotNull MainCallParameters mainCallParameters) {
+    public String generateProgramCode(@NotNull List<JetFile> files, @NotNull MainCallParameters mainCallParameters)
+            throws TranslationException {
         JsProgram program = generateProgram(files, mainCallParameters);
         CodeGenerator generator = new CodeGenerator();
         return generator.generateToString(program);
     }
 
     @NotNull
-    public JsProgram generateProgram(@NotNull List<JetFile> filesToTranslate, @NotNull MainCallParameters mainCallParameters) {
+    public JsProgram generateProgram(@NotNull List<JetFile> filesToTranslate, @NotNull MainCallParameters mainCallParameters)
+            throws TranslationException {
         JetStandardLibrary.initialize(config.getProject());
         BindingContext bindingContext = AnalyzerFacadeForJS.analyzeFilesAndCheckErrors(filesToTranslate, config);
         Collection<JetFile> files = AnalyzerFacadeForJS.withJsLibAdded(filesToTranslate, config);
diff --git a/js/js.translator/src/org/jetbrains/k2js/facade/exceptions/TranslationException.java b/js/js.translator/src/org/jetbrains/k2js/facade/exceptions/TranslationException.java
new file mode 100644
index 00000000000..54483d8f5ec
--- /dev/null
+++ b/js/js.translator/src/org/jetbrains/k2js/facade/exceptions/TranslationException.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2010-2012 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.k2js.facade.exceptions;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * @author Pavel Talanov
+ */
+public class TranslationException extends Exception {
+
+    public TranslationException(@NotNull Throwable cause) {
+        super(cause);
+    }
+
+    public TranslationException(@NotNull String message, @NotNull Exception cause) {
+        super(message, cause);
+    }
+}
diff --git a/js/js.translator/src/org/jetbrains/k2js/facade/exceptions/TranslationInternalException.java b/js/js.translator/src/org/jetbrains/k2js/facade/exceptions/TranslationInternalException.java
new file mode 100644
index 00000000000..c2cf42247cd
--- /dev/null
+++ b/js/js.translator/src/org/jetbrains/k2js/facade/exceptions/TranslationInternalException.java
@@ -0,0 +1,29 @@
+/*
+ * Copyright 2010-2012 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.k2js.facade.exceptions;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * @author Pavel Talanov
+ */
+public class TranslationInternalException extends TranslationException {
+
+    public TranslationInternalException(@NotNull Throwable cause) {
+        super(cause);
+    }
+}
diff --git a/js/js.translator/src/org/jetbrains/k2js/facade/exceptions/UnsupportedFeatureException.java b/js/js.translator/src/org/jetbrains/k2js/facade/exceptions/UnsupportedFeatureException.java
new file mode 100644
index 00000000000..3806043ba5a
--- /dev/null
+++ b/js/js.translator/src/org/jetbrains/k2js/facade/exceptions/UnsupportedFeatureException.java
@@ -0,0 +1,29 @@
+/*
+ * Copyright 2010-2012 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.k2js.facade.exceptions;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * @author Pavel Talanov
+ */
+public class UnsupportedFeatureException extends TranslationException {
+
+    public UnsupportedFeatureException(@NotNull String message, @NotNull Exception cause) {
+        super(message, cause);
+    }
+}
diff --git a/js/js.translator/src/org/jetbrains/k2js/translate/general/Translation.java b/js/js.translator/src/org/jetbrains/k2js/translate/general/Translation.java
index 54a65a1cc77..94595f723c8 100644
--- a/js/js.translator/src/org/jetbrains/k2js/translate/general/Translation.java
+++ b/js/js.translator/src/org/jetbrains/k2js/translate/general/Translation.java
@@ -26,6 +26,9 @@ import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.BindingContext;
 import org.jetbrains.jet.lang.types.lang.JetStandardLibrary;
 import org.jetbrains.k2js.facade.MainCallParameters;
+import org.jetbrains.k2js.facade.exceptions.TranslationInternalException;
+import org.jetbrains.k2js.facade.exceptions.TranslationException;
+import org.jetbrains.k2js.facade.exceptions.UnsupportedFeatureException;
 import org.jetbrains.k2js.translate.context.StaticContext;
 import org.jetbrains.k2js.translate.context.TranslationContext;
 import org.jetbrains.k2js.translate.declaration.ClassTranslator;
@@ -138,7 +141,21 @@ public final class Translation {
 
     @NotNull
     public static JsProgram generateAst(@NotNull BindingContext bindingContext,
-            @NotNull List<JetFile> files, @NotNull MainCallParameters mainCallParameters) {
+            @NotNull List<JetFile> files, @NotNull MainCallParameters mainCallParameters) throws TranslationException {
+        try {
+            return doGenerateAst(bindingContext, files, mainCallParameters);
+        }
+        catch (UnsupportedOperationException e) {
+            throw new UnsupportedFeatureException("Unsupported feature used.", e);
+        }
+        catch (Throwable e) {
+            throw new TranslationInternalException(e);
+        }
+    }
+
+    @NotNull
+    private static JsProgram doGenerateAst(@NotNull BindingContext bindingContext, @NotNull List<JetFile> files,
+            @NotNull MainCallParameters mainCallParameters) {
         //TODO: move some of the code somewhere
         JetStandardLibrary standardLibrary = JetStandardLibrary.getInstance();
         StaticContext staticContext = StaticContext.generateStaticContext(standardLibrary, bindingContext);