diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DescriptorResolver.java b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DescriptorResolver.java
index 1a3f60d7b60..9e33fc83583 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DescriptorResolver.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DescriptorResolver.java
@@ -1152,33 +1152,33 @@ public class DescriptorResolver {
         List<TypeProjection> arguments = type.getArguments();
         assert parameters.size() == arguments.size();
 
-        List<KtTypeReference> jetTypeArguments = typeElement.getTypeArgumentsAsTypes();
+        List<KtTypeReference> ktTypeArguments = typeElement.getTypeArgumentsAsTypes();
 
         // A type reference from Kotlin code can yield a flexible type only if it's `ft<T1, T2>`, whose bounds should not be checked
         if (FlexibleTypesKt.isFlexible(type) && !DynamicTypesKt.isDynamic(type)) {
-            assert jetTypeArguments.size() == 2
+            assert ktTypeArguments.size() == 2
                     : "Flexible type cannot be denoted in Kotlin otherwise than as ft<T1, T2>, but was: "
                       + PsiUtilsKt.getElementTextWithContext(typeReference);
             // it's really ft<Foo, Bar>
             FlexibleType flexibleType = FlexibleTypesKt.asFlexibleType(type);
-            checkBounds(jetTypeArguments.get(0), flexibleType.getLowerBound(), trace);
-            checkBounds(jetTypeArguments.get(1), flexibleType.getUpperBound(), trace);
+            checkBounds(ktTypeArguments.get(0), flexibleType.getLowerBound(), trace);
+            checkBounds(ktTypeArguments.get(1), flexibleType.getUpperBound(), trace);
             return;
         }
 
-        assert jetTypeArguments.size() <= arguments.size() : typeElement.getText() + ": " + jetTypeArguments + " - " + arguments;
+        // If the numbers of type arguments do not match, the error has been already reported in TypeResolver
+        if (ktTypeArguments.size() != arguments.size()) return;
 
         TypeSubstitutor substitutor = TypeSubstitutor.create(type);
-        for (int i = 0; i < jetTypeArguments.size(); i++) {
-            KtTypeReference jetTypeArgument = jetTypeArguments.get(i);
-
-            if (jetTypeArgument == null) continue;
+        for (int i = 0; i < ktTypeArguments.size(); i++) {
+            KtTypeReference ktTypeArgument = ktTypeArguments.get(i);
+            if (ktTypeArgument == null) continue;
 
             KotlinType typeArgument = arguments.get(i).getType();
-            checkBounds(jetTypeArgument, typeArgument, trace);
+            checkBounds(ktTypeArgument, typeArgument, trace);
 
             TypeParameterDescriptor typeParameterDescriptor = parameters.get(i);
-            checkBounds(jetTypeArgument, typeArgument, typeParameterDescriptor, substitutor, trace);
+            checkBounds(ktTypeArgument, typeArgument, typeParameterDescriptor, substitutor, trace);
         }
     }
 
diff --git a/compiler/testData/diagnostics/tests/regressions/kt9620.kt b/compiler/testData/diagnostics/tests/regressions/kt9620.kt
new file mode 100644
index 00000000000..086014b0c61
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt9620.kt
@@ -0,0 +1,14 @@
+// KT-9620 AssertionError in checkBounds
+
+interface E1<T : D<!TYPE_ARGUMENTS_NOT_ALLOWED!><String><!>, D>
+
+interface A
+interface B
+interface D<X>
+interface E2<T : D<!TYPE_ARGUMENTS_NOT_ALLOWED!><A><!>, D<!SYNTAX!><<!><!SYNTAX!>B<!><!SYNTAX!>><!><!SYNTAX!>><!>
+
+// KT-11354 AE from DescriptorResolver
+
+open class L<E>()
+
+class M<C> : L<C<!TYPE_ARGUMENTS_NOT_ALLOWED!><C><!>>()
diff --git a/compiler/testData/diagnostics/tests/regressions/kt9620.txt b/compiler/testData/diagnostics/tests/regressions/kt9620.txt
new file mode 100644
index 00000000000..5634315258f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt9620.txt
@@ -0,0 +1,45 @@
+package
+
+public interface A {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface B {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface D</*0*/ X> {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface E1</*0*/ T : D, /*1*/ D> {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface E2</*0*/ T : D, /*1*/ D> {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public open class L</*0*/ E> {
+    public constructor L</*0*/ E>()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class M</*0*/ C> : L<C> {
+    public constructor M</*0*/ C>()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
index 94c13d3dd1b..0326caa2846 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
@@ -14898,6 +14898,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("kt9620.kt")
+            public void testKt9620() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/regressions/kt9620.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("kt9633.kt")
             public void testKt9633() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/regressions/kt9633.kt");