diff --git a/taiga/projects/attachments/services.py b/taiga/projects/attachments/services.py
index 0c5ac4a0..ae2388ce 100644
--- a/taiga/projects/attachments/services.py
+++ b/taiga/projects/attachments/services.py
@@ -15,12 +15,13 @@
 
 from django.conf import settings
 
-from taiga.base.utils.thumbnails import get_thumbnail_url
+from taiga.base.utils.thumbnails import get_thumbnail_url, get_thumbnail
 
 
-def get_timeline_image_thumbnail_url(attachment):
+def get_timeline_image_thumbnail_name(attachment):
     if attachment.attached_file:
-        return get_thumbnail_url(attachment.attached_file, settings.THN_ATTACHMENT_TIMELINE)
+        thumbnail = get_thumbnail(attachment.attached_file, settings.THN_ATTACHMENT_TIMELINE)
+        return thumbnail.name if thumbnail else None
     return None
 
 
@@ -29,6 +30,7 @@ def get_card_image_thumbnail_url(attachment):
         return get_thumbnail_url(attachment.attached_file, settings.THN_ATTACHMENT_CARD)
     return None
 
+
 def get_attachment_image_preview_url(attachment):
     if attachment.attached_file:
         return get_thumbnail_url(attachment.attached_file, settings.THN_ATTACHMENT_PREVIEW)
diff --git a/taiga/projects/history/freeze_impl.py b/taiga/projects/history/freeze_impl.py
index 14091920..12e4a753 100644
--- a/taiga/projects/history/freeze_impl.py
+++ b/taiga/projects/history/freeze_impl.py
@@ -28,7 +28,7 @@ from taiga.base.utils.iterators import as_tuple
 from taiga.base.utils.iterators import as_dict
 from taiga.mdrender.service import render as mdrender
 
-from taiga.projects.attachments.services import get_timeline_image_thumbnail_url
+from taiga.projects.attachments.services import get_timeline_image_thumbnail_name
 
 import os
 
@@ -199,12 +199,13 @@ def _generic_extract(obj:object, fields:list, default=None) -> dict:
 def extract_attachments(obj) -> list:
     for attach in obj.attachments.all():
         # Force the creation of a thumbnail for the timeline
-        get_timeline_image_thumbnail_url(attach)
+        thumbnail_file = get_timeline_image_thumbnail_name(attach)
 
         yield {"id": attach.id,
                "filename": os.path.basename(attach.attached_file.name),
                "url": attach.attached_file.url,
                "attached_file": str(attach.attached_file),
+               "thumbnail_file": thumbnail_file,
                "is_deprecated": attach.is_deprecated,
                "description": attach.description,
                "order": attach.order}
diff --git a/taiga/timeline/serializers.py b/taiga/timeline/serializers.py
index fb914c24..4f89ee69 100644
--- a/taiga/timeline/serializers.py
+++ b/taiga/timeline/serializers.py
@@ -85,7 +85,12 @@ class TimelineSerializer(serializers.LightSerializer):
             attached_file = file_path[index+1:]
 
         item['url'] = default_storage.url(attached_file)
-        thumb_url = get_thumbnail_url(attached_file,
-                                      settings.THN_ATTACHMENT_TIMELINE)
+
+        if 'thumbnail_file' in item:
+            thumb_file = item['thumbnail_file']
+            thumb_url = default_storage.url(thumb_file) if thumb_file else None
+        else:
+            thumb_url = get_thumbnail_url(attached_file,
+                                          settings.THN_ATTACHMENT_TIMELINE)
 
         item['thumb_url'] = thumb_url