diff --git a/heat/engine/clients/os/swift.py b/heat/engine/clients/os/swift.py
index 8919c84ac6..4dd59726b4 100644
--- a/heat/engine/clients/os/swift.py
+++ b/heat/engine/clients/os/swift.py
@@ -166,7 +166,10 @@ class SwiftClientPlugin(client_plugin.ClientPlugin):
                 file_name = obj['name']
                 if file_name not in files_to_skip:
                     contents = client.get_object(files_container, file_name)[1]
-                files[file_name] = contents
+                    if isinstance(contents, bytes):
+                        files[file_name] = contents.decode(encoding='utf-8')
+                    else:
+                        files[file_name] = contents
         except exceptions.ClientException as cex:
             raise exception.NotFound(_('Could not fetch files from '
                                        'container %(container)s, '
diff --git a/releasenotes/notes/heat-decode-files-read-from-containers-fe2bbb0b48a69717.yaml b/releasenotes/notes/heat-decode-files-read-from-containers-fe2bbb0b48a69717.yaml
new file mode 100644
index 0000000000..45c8a893cb
--- /dev/null
+++ b/releasenotes/notes/heat-decode-files-read-from-containers-fe2bbb0b48a69717.yaml
@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixed the consistent type mismatch error caused by creating or updating
+    a stack with files stored in OpenStack Swift containers, using
+    the `files_container` parameter. Now file content is always decoded and
+    can be used as a string value.