diff --git a/boards/models/post/sync.py b/boards/models/post/sync.py
--- a/boards/models/post/sync.py
+++ b/boards/models/post/sync.py
@@ -6,6 +6,7 @@ from boards.models import KeyPair, Globa
 from boards.models.attachment.downloaders import download
 from boards.utils import get_file_mimetype, get_file_hash
 from django.db import transaction
+from django import forms
 
 EXCEPTION_NODE = 'Sync node returned an error: {}.'
 EXCEPTION_DOWNLOAD = 'File was not downloaded.'
@@ -236,15 +237,20 @@ class SyncManager:
                     tag_ref = tag_refs.find("{}[@ref='{}']".format(
                         TAG_ATTACHMENT_REF, attachment.text))
                     url = tag_ref.get(ATTR_URL)
-                    attached_file = download(hostname + url)
-                    if attached_file is None:
-                        raise SyncException(EXCEPTION_DOWNLOAD)
+                    try:
+                        attached_file = download(hostname + url)
+
+                        if attached_file is None:
+                            raise SyncException(EXCEPTION_DOWNLOAD)
 
-                    hash = get_file_hash(attached_file)
-                    if hash != attachment.text:
-                        raise SyncException(EXCEPTION_HASH)
+                        hash = get_file_hash(attached_file)
+                        if hash != attachment.text:
+                            raise SyncException(EXCEPTION_HASH)
 
-                    files.append(attached_file)
+                        files.append(attached_file)
+                    except forms.ValidationError:
+                        urls.append(hostname+url)
+                        
 
             if is_old:
                 post = global_id.post