diff --git a/libs/appfunctions/api/current.txt b/libs/appfunctions/api/current.txt
index 89cdba8..faf84a8 100644
--- a/libs/appfunctions/api/current.txt
+++ b/libs/appfunctions/api/current.txt
@@ -52,9 +52,10 @@
     field public static final int RESULT_CANCELLED = 2001; // 0x7d1
     field public static final int RESULT_DENIED = 1000; // 0x3e8
     field public static final int RESULT_DISABLED = 1002; // 0x3ea
-    field public static final int RESULT_INTERNAL_ERROR = 2000; // 0x7d0
+    field public static final int RESULT_FUNCTION_NOT_FOUND = 1003; // 0x3eb
     field public static final int RESULT_INVALID_ARGUMENT = 1001; // 0x3e9
     field public static final int RESULT_OK = 0; // 0x0
+    field public static final int RESULT_SYSTEM_ERROR = 2000; // 0x7d0
   }
 
 }
diff --git a/libs/appfunctions/java/com/google/android/appfunctions/sidecar/ExecuteAppFunctionResponse.java b/libs/appfunctions/java/com/google/android/appfunctions/sidecar/ExecuteAppFunctionResponse.java
index bf4ab45..4e88fb0 100644
--- a/libs/appfunctions/java/com/google/android/appfunctions/sidecar/ExecuteAppFunctionResponse.java
+++ b/libs/appfunctions/java/com/google/android/appfunctions/sidecar/ExecuteAppFunctionResponse.java
@@ -76,18 +76,23 @@
     /**
      * The caller tried to execute a disabled app function.
      *
-     * <p>This error is in the request error category.
-     *
      * <p>This error is in the {@link #ERROR_CATEGORY_REQUEST_ERROR} category.
      */
     public static final int RESULT_DISABLED = 1002;
 
     /**
+     * The caller tried to execute a function that does not exist.
+     *
+     * <p>This error is in the {@link #ERROR_CATEGORY_REQUEST_ERROR} category.
+     */
+    public static final int RESULT_FUNCTION_NOT_FOUND = 1003;
+
+    /**
      * An internal unexpected error coming from the system.
      *
      * <p>This error is in the {@link #ERROR_CATEGORY_SYSTEM} category.
      */
-    public static final int RESULT_INTERNAL_ERROR = 2000;
+    public static final int RESULT_SYSTEM_ERROR = 2000;
 
     /**
      * The operation was cancelled. Use this error code to report that a cancellation is done after
@@ -327,7 +332,8 @@
                 RESULT_OK,
                 RESULT_DENIED,
                 RESULT_APP_UNKNOWN_ERROR,
-                RESULT_INTERNAL_ERROR,
+                RESULT_SYSTEM_ERROR,
+                RESULT_FUNCTION_NOT_FOUND,
                 RESULT_INVALID_ARGUMENT,
                 RESULT_DISABLED,
                 RESULT_CANCELLED
diff --git a/libs/appfunctions/tests/src/com/google/android/appfunctions/sidecar/tests/SidecarConverterTest.kt b/libs/appfunctions/tests/src/com/google/android/appfunctions/sidecar/tests/SidecarConverterTest.kt
index 1f9fddd..264f842 100644
--- a/libs/appfunctions/tests/src/com/google/android/appfunctions/sidecar/tests/SidecarConverterTest.kt
+++ b/libs/appfunctions/tests/src/com/google/android/appfunctions/sidecar/tests/SidecarConverterTest.kt
@@ -105,7 +105,7 @@
         val emptyGd = GenericDocument.Builder<GenericDocument.Builder<*>>("", "", "").build()
         val platformResponse =
             ExecuteAppFunctionResponse.newFailure(
-                ExecuteAppFunctionResponse.RESULT_INTERNAL_ERROR,
+                ExecuteAppFunctionResponse.RESULT_SYSTEM_ERROR,
                 null,
                 null
             )
@@ -119,7 +119,7 @@
         assertThat(sidecarResponse.resultDocument.id).isEqualTo(emptyGd.id)
         assertThat(sidecarResponse.resultDocument.schemaType).isEqualTo(emptyGd.schemaType)
         assertThat(sidecarResponse.resultCode)
-            .isEqualTo(ExecuteAppFunctionResponse.RESULT_INTERNAL_ERROR)
+            .isEqualTo(ExecuteAppFunctionResponse.RESULT_SYSTEM_ERROR)
         assertThat(sidecarResponse.errorMessage).isNull()
     }
 
@@ -152,7 +152,7 @@
         val emptyGd = GenericDocument.Builder<GenericDocument.Builder<*>>("", "", "").build()
         val sidecarResponse =
             com.google.android.appfunctions.sidecar.ExecuteAppFunctionResponse.newFailure(
-                ExecuteAppFunctionResponse.RESULT_INTERNAL_ERROR,
+                ExecuteAppFunctionResponse.RESULT_SYSTEM_ERROR,
                 null,
                 null
             )
@@ -166,7 +166,7 @@
         assertThat(platformResponse.resultDocument.id).isEqualTo(emptyGd.id)
         assertThat(platformResponse.resultDocument.schemaType).isEqualTo(emptyGd.schemaType)
         assertThat(platformResponse.resultCode)
-            .isEqualTo(ExecuteAppFunctionResponse.RESULT_INTERNAL_ERROR)
+            .isEqualTo(ExecuteAppFunctionResponse.RESULT_SYSTEM_ERROR)
         assertThat(platformResponse.errorMessage).isNull()
     }
 }