diff --git a/crawl4ai/async_configs.py b/crawl4ai/async_configs.py
index 15789be1e..d3eb96035 100644
--- a/crawl4ai/async_configs.py
+++ b/crawl4ai/async_configs.py
@@ -2398,6 +2398,8 @@ def to_dict(self):
             "disable_cache": self.disable_cache,
             "no_cache_read": self.no_cache_read,
             "no_cache_write": self.no_cache_write,
+            "check_cache_freshness": self.check_cache_freshness,
+            "cache_validation_timeout": self.cache_validation_timeout,
             "shared_data": self.shared_data,
             "wait_until": self.wait_until,
             "page_timeout": self.page_timeout,
@@ -2424,6 +2426,7 @@ def to_dict(self):
             "override_navigator": self.override_navigator,
             "magic": self.magic,
             "adjust_viewport_to_content": self.adjust_viewport_to_content,
+            "virtual_scroll_config": self.virtual_scroll_config,
             "screenshot": self.screenshot,
             "screenshot_wait_for": self.screenshot_wait_for,
             "screenshot_height_threshold": self.screenshot_height_threshold,
@@ -2461,6 +2464,7 @@ def to_dict(self):
             "match_mode": self.match_mode,
             "experimental": self.experimental,
             "max_retries": self.max_retries,
+            "fallback_fetch_function": self.fallback_fetch_function,
         }
 
     def clone(self, **kwargs):
diff --git a/tests/unit/test_run_config_clone_fields.py b/tests/unit/test_run_config_clone_fields.py
new file mode 100644
index 000000000..fe583c4fe
--- /dev/null
+++ b/tests/unit/test_run_config_clone_fields.py
@@ -0,0 +1,38 @@
+"""CrawlerRunConfig.clone() must carry over fields that to_dict() used to drop."""
+
+from crawl4ai import CrawlerRunConfig
+from crawl4ai.async_configs import VirtualScrollConfig
+
+
+async def _fallback(url: str) -> str:
+    return "<html><body>fallback</body></html>"
+
+
+def test_clone_preserves_fallback_fetch_function():
+    config = CrawlerRunConfig(fallback_fetch_function=_fallback)
+
+    cloned = config.clone(deep_crawl_strategy=None, stream=True)
+
+    assert cloned.fallback_fetch_function is _fallback
+    assert cloned.stream is True
+
+
+def test_clone_can_override_fallback_fetch_function():
+    config = CrawlerRunConfig(fallback_fetch_function=_fallback)
+
+    assert config.clone(fallback_fetch_function=None).fallback_fetch_function is None
+
+
+def test_clone_preserves_cache_validation_and_virtual_scroll():
+    scroll = VirtualScrollConfig(container_selector="#feed")
+    config = CrawlerRunConfig(
+        check_cache_freshness=True,
+        cache_validation_timeout=3.5,
+        virtual_scroll_config=scroll,
+    )
+
+    cloned = config.clone(stream=True)
+
+    assert cloned.check_cache_freshness is True
+    assert cloned.cache_validation_timeout == 3.5
+    assert cloned.virtual_scroll_config is scroll