diff --git a/freqtrade/data/history.py b/freqtrade/data/history.py
index 80a846e87..189f51594 100644
--- a/freqtrade/data/history.py
+++ b/freqtrade/data/history.py
@@ -239,10 +239,12 @@ def _load_cached_data_for_updating(pair: str, timeframe: str, timerange: Optiona
                                    timerange=None, fill_missing=False,
                                    drop_incomplete=True, warn_no_data=False)
     if not data.empty:
-        if start < data.iloc[0]['date']:
+        if start and start < data.iloc[0]['date']:
             # Earlier data than existing data requested, redownload all
             return DataFrame(columns=DEFAULT_DATAFRAME_COLUMNS), None
+
         start = data.iloc[-1]['date']
+
     start_ms = int(start.timestamp() * 1000) if start else None
     return data, start_ms
 
diff --git a/tests/data/test_history.py b/tests/data/test_history.py
index 973c83a46..c626e27e8 100644
--- a/tests/data/test_history.py
+++ b/tests/data/test_history.py
@@ -301,7 +301,9 @@ def test_download_pair_history2(mocker, default_conf, testdatadir) -> None:
         [1509836520000, 0.00162008, 0.00162008, 0.00162008, 0.00162008, 108.14853839],
         [1509836580000, 0.00161, 0.00161, 0.00161, 0.00161, 82.390199]
     ]
-    json_dump_mock = mocker.patch('freqtrade.misc.file_dump_json', return_value=None)
+    json_dump_mock = mocker.patch(
+        'freqtrade.data.datahandlers.jsondatahandler.JsonDataHandler.ohlcv_store',
+        return_value=None)
     mocker.patch('freqtrade.exchange.Exchange.get_historic_ohlcv', return_value=tick)
     exchange = get_patched_exchange(mocker, default_conf)
     _download_pair_history(testdatadir, exchange, pair="UNITTEST/BTC", timeframe='1m')