diff --git a/src/graphql/execution/execute.py b/src/graphql/execution/execute.py
index 58488f8f..35bddba4 100644
--- a/src/graphql/execution/execute.py
+++ b/src/graphql/execution/execute.py
@@ -1984,6 +1984,13 @@ async def yield_subsequent_payloads(
                     break
 
 
+UNEXPECTED_EXPERIMENTAL_DIRECTIVES = (
+    "The provided schema unexpectedly contains experimental directives"
+    " (@defer or @stream). These directives may only be utilized"
+    " if experimental execution features are explicitly enabled."
+)
+
+
 UNEXPECTED_MULTIPLE_PAYLOADS = (
     "Executing this GraphQL operation would unexpectedly produce multiple payloads"
     " (due to @defer or @stream directive)"
@@ -2016,10 +2023,12 @@ def execute(
 
     This function does not support incremental delivery (`@defer` and `@stream`).
     If an operation that defers or streams data is executed with this function,
-    it will throw or resolve to an object containing an error instead.
-    Use `experimental_execute_incrementally` if you want to support incremental
-    delivery.
+    it will throw an error instead. Use `experimental_execute_incrementally` if
+    you want to support incremental delivery.
     """
+    if schema.get_directive("defer") or schema.get_directive("stream"):
+        raise GraphQLError(UNEXPECTED_EXPERIMENTAL_DIRECTIVES)
+
     result = experimental_execute_incrementally(
         schema,
         document,
@@ -2043,9 +2052,7 @@ async def await_result() -> Any:
         awaited_result = await result
         if isinstance(awaited_result, ExecutionResult):
             return awaited_result
-        return ExecutionResult(
-            None, errors=[GraphQLError(UNEXPECTED_MULTIPLE_PAYLOADS)]
-        )
+        raise GraphQLError(UNEXPECTED_MULTIPLE_PAYLOADS)
 
     return await_result()
 
diff --git a/tests/execution/test_defer.py b/tests/execution/test_defer.py
index 866a1c13..ff17c9f0 100644
--- a/tests/execution/test_defer.py
+++ b/tests/execution/test_defer.py
@@ -962,15 +962,10 @@ async def original_execute_function_throws_error_if_deferred_and_not_all_is_sync
             """
         )
 
-        result = await execute(schema, document, {})  # type: ignore
+        with pytest.raises(GraphQLError) as exc_info:
+            await execute(schema, document, {})  # type: ignore
 
-        assert result == (
-            None,
-            [
-                {
-                    "message": "Executing this GraphQL operation would unexpectedly"
-                    " produce multiple payloads"
-                    " (due to @defer or @stream directive)"
-                }
-            ],
+        assert str(exc_info.value) == (
+            "Executing this GraphQL operation would unexpectedly produce"
+            " multiple payloads (due to @defer or @stream directive)"
         )
diff --git a/tests/execution/test_executor.py b/tests/execution/test_executor.py
index 61f4ba62..fd80051b 100644
--- a/tests/execution/test_executor.py
+++ b/tests/execution/test_executor.py
@@ -9,6 +9,7 @@
 from graphql.type import (
     GraphQLArgument,
     GraphQLBoolean,
+    GraphQLDeferDirective,
     GraphQLField,
     GraphQLInt,
     GraphQLInterfaceType,
@@ -18,6 +19,7 @@
     GraphQLResolveInfo,
     GraphQLScalarType,
     GraphQLSchema,
+    GraphQLStreamDirective,
     GraphQLString,
     GraphQLUnionType,
     ResponsePath,
@@ -786,6 +788,38 @@ class Data:
         result = execute_sync(schema, document, Data(), operation_name="S")
         assert result == ({"a": "b"}, None)
 
+    def errors_when_using_original_execute_with_schemas_including_experimental_defer():
+        schema = GraphQLSchema(
+            query=GraphQLObjectType("Q", {"a": GraphQLField(GraphQLString)}),
+            directives=[GraphQLDeferDirective],
+        )
+        document = parse("query Q { a }")
+
+        with pytest.raises(GraphQLError) as exc_info:
+            execute(schema, document)
+
+        assert str(exc_info.value) == (
+            "The provided schema unexpectedly contains experimental directives"
+            " (@defer or @stream). These directives may only be utilized"
+            " if experimental execution features are explicitly enabled."
+        )
+
+    def errors_when_using_original_execute_with_schemas_including_experimental_stream():
+        schema = GraphQLSchema(
+            query=GraphQLObjectType("Q", {"a": GraphQLField(GraphQLString)}),
+            directives=[GraphQLStreamDirective],
+        )
+        document = parse("query Q { a }")
+
+        with pytest.raises(GraphQLError) as exc_info:
+            execute(schema, document)
+
+        assert str(exc_info.value) == (
+            "The provided schema unexpectedly contains experimental directives"
+            " (@defer or @stream). These directives may only be utilized"
+            " if experimental execution features are explicitly enabled."
+        )
+
     def resolves_to_an_error_if_schema_does_not_support_operation():
         schema = GraphQLSchema(assume_valid=True)