Try to be more helpful

changedetectionio/content_fetcher.py

@@ -77,11 +77,12 @@ class ScreenshotUnavailable(Exception):
 
 
 class ReplyWithContentButNoText(Exception):
-    def __init__(self, status_code, url, screenshot=None):
+    def __init__(self, status_code, url, screenshot=None, has_filters=False):
         # Set this so we can use it in other parts of the app
         self.status_code = status_code
         self.url = url
         self.screenshot = screenshot
+        self.has_filters = has_filters
         return
 
 

changedetectionio/processors/text_json_diff.py

@@ -314,7 +314,7 @@ class perform_site_check(difference_detection_processor):
         # Treat pages with no renderable text content as a change? No by default
         empty_pages_are_a_change = self.datastore.data['settings']['application'].get('empty_pages_are_a_change', False)
         if not is_json and not empty_pages_are_a_change and len(stripped_text_from_html.strip()) == 0:
-            raise content_fetcher.ReplyWithContentButNoText(url=url, status_code=fetcher.get_last_status_code(), screenshot=screenshot)
+            raise content_fetcher.ReplyWithContentButNoText(url=url, status_code=fetcher.get_last_status_code(), screenshot=screenshot, has_filters=has_filter_rule)
 
         # We rely on the actual text in the html output.. many sites have random script vars etc,
         # in the future we'll implement other mechanisms.

changedetectionio/update_worker.py

@@ -251,7 +251,11 @@ class update_worker(threading.Thread):
                         # Totally fine, it's by choice - just continue on, nothing more to care about
                         # Page had elements/content but no renderable text
                         # Backend (not filters) gave zero output
-                        self.datastore.update_watch(uuid=uuid, update_obj={'last_error': "Got HTML content but no text found (With {} reply code).".format(e.status_code)})
+                        if e.has_filters:
+                            self.datastore.update_watch(uuid=uuid, update_obj={'last_error': f"Got HTML content but no text found (With {e.status_code} reply code), it's possible that the filters you have give an empty result or contain only an image <a href=\"https://github.com/dgtlmoon/changedetection.io/wiki/Detecting-changes-in-images\">more help here</a>"})
+                        else:
+                            self.datastore.update_watch(uuid=uuid, update_obj={'last_error': f"Got HTML content but no text found (With {e.status_code} reply code)."})
+
                         if e.screenshot:
                             self.datastore.save_screenshot(watch_uuid=uuid, screenshot=e.screenshot)
                         process_changedetection_results = False