diff --git a/esmvalcore/esgf/_search.py b/esmvalcore/esgf/_search.py
index 4f97b527f7..7807e25eaa 100644
--- a/esmvalcore/esgf/_search.py
+++ b/esmvalcore/esgf/_search.py
@@ -110,7 +110,12 @@ def _search_index_nodes(facets):
             )
             FIRST_ONLINE_INDEX_NODE = url
             return results
-        except requests.exceptions.Timeout as error:
+        except (
+            requests.exceptions.ConnectionError,
+            requests.exceptions.HTTPError,
+            requests.exceptions.Timeout,
+        ) as error:
+            logger.debug("Unable to connect to %s due to %s", url, error)
             errors.append(error)
 
     raise FileNotFoundError("Failed to search ESGF, unable to connect:\n" +