diff --git a/dl_coursera/Crawler.py b/dl_coursera/Crawler.py
index d0dd566..72b6fa0 100644
--- a/dl_coursera/Crawler.py
+++ b/dl_coursera/Crawler.py
@@ -372,7 +372,8 @@ def _get_uid(s: str):
                     break
 
             if not self._uid:
-                raise UserIDNotFoundException()
+                logging.warning("UserID not found in cookies, but ignoring as it seems unused.")
+                # raise UserIDNotFoundException()
 
     def crawl(self, *, slug, is_spec):
         if not self._loggedin:
diff --git a/dl_coursera/DLTaskGatherer.py b/dl_coursera/DLTaskGatherer.py
index 5e0cbb3..bb80632 100644
--- a/dl_coursera/DLTaskGatherer.py
+++ b/dl_coursera/DLTaskGatherer.py
@@ -2,6 +2,7 @@
 import zipfile
 import io
 import logging
+import re
 
 from .lib.ExploringTree import ExploringTree
 
@@ -10,6 +11,8 @@
 from .resource import load_resource
 from .define import *
 
+def _sanitize_filename(s):
+    return re.sub(r'[<>:"/\\|?*]', '_', s)
 
 def _shorten_slug(x):
     if len(x['slug']) > 40:
@@ -191,4 +194,6 @@ def _gather_cml(self, cml, i, supplement):
             self._gather_asset(asset)
 
     def _gather_asset(self, asset):
-        self._add_dl_task(asset['url'], self._see(asset['name']))
+        self._add_dl_task(
+            asset['url'], self._see(_sanitize_filename(asset['name']))
+        )