diff --git a/dokuWikiDumper/dump/content/__init__.py b/dokuWikiDumper/dump/content/__init__.py
index 665d509..9c88dcc 100644
--- a/dokuWikiDumper/dump/content/__init__.py
+++ b/dokuWikiDumper/dump/content/__init__.py
@@ -153,6 +153,9 @@ def dump_page(dumpDir: str,
             except DispositionHeaderMissingError:
                 print(msg_header, '    Revision %s of [[%s]] is empty. (probably deleted)' % (
                     rev['id'], title))
+        else:
+            print(msg_header, '    Revision %s of [[%s]] failed: %s' % (rev['id'], title, 'Rev id not found (please check ?do=revisions of this page)'))
+
 
             # time.sleep(1.5)
 
diff --git a/dokuWikiDumper/dump/content/revisions.py b/dokuWikiDumper/dump/content/revisions.py
index 3afc349..85a8450 100644
--- a/dokuWikiDumper/dump/content/revisions.py
+++ b/dokuWikiDumper/dump/content/revisions.py
@@ -298,6 +298,8 @@ def save_page_changes(dumpDir, title: str, revs, child_path, msg_header: str):
                     rev_id = None
                     
             assert rev_id is not None, 'Cannot parse date: %s' % rev['date']
+            assert isinstance(rev_id, str), 'rev_id must be str, not %s' % type(rev_id)
+
             # if rev_id is not unique, plus 1 to it until it is.
             while rev_id in revidOfPage:
                 rev_id = str(int(rev_id) + 1)
diff --git a/dokuWikiDumper/dump/html/html.py b/dokuWikiDumper/dump/html/html.py
index f020f54..81a649b 100644
--- a/dokuWikiDumper/dump/html/html.py
+++ b/dokuWikiDumper/dump/html/html.py
@@ -104,7 +104,8 @@ def dump_html_page(dumpDir, index_of_title, title, doku_url, session: requests.S
                 print(msg_header, '    Revision %s of [[%s]] saved.' % (rev['id'], title))
             except requests.HTTPError as e:
                 print(msg_header, '    Revision %s of [[%s]] failed: %s' % (rev['id'], title, e))
-    
+        else:
+            print(msg_header, '    Revision %s of [[%s]] failed: %s' % (rev['id'], title, 'Rev id not found (please check ?do=revisions of this page)'))
 
     save_page_changes(dumpDir=dumpDir, child_path=child_path, title=title, 
                        revs=revs, msg_header=msg_header)
\ No newline at end of file