Close position from MT5 Python API not working

Question

I'm trying to close an existing position in MT5 from Python but MT5 always claims an 'Unsupported Filling Mode'.
I tried all possible filling modes but always get the same result. Same, if I omit the filling mode in the request. I also tried to fetch the filling mode from the symbol info and used it in the request - without success. This happens on a live account.
Here is my function that takes an existing position and sends a close request for that position:

async def ClosePosition(position):
   if (position.type == mt5.POSITION_TYPE_BUY):
       order_type = mt5.ORDER_TYPE_SELL
       price = mt5.symbol_info_tick(position.symbol).bid
   else:
       order_type = mt5.ORDER_TYPE_BUY
       price = mt5.symbol_info_tick(position.symbol).ask

   request = {
           "action": mt5.TRADE_ACTION_DEAL,
           "symbol": position.symbol,
           "volume": position.volume,
           "type": order_type,
           "position": position.ticket,
           "price": price,
           "deviation": 10,
           "magic": 0,
           "comment": "Closed by Python",
           "type_time": mt5.ORDER_TIME_GTC,
           "type_filling": mt5.ORDER_FILLING_RETURN
       }

   result = mt5.order_send(request)

This is what the journal says:
Trades '#######': failed market buy 0.01 CHFJPY, close #109459760 sell 0.01 CHFJPY 116.807 [Unsupported filling mode]

Any help is greatly appreciated.

Answer 1

Eventually I found that the values of SYMBOL_FILLING_MODE do not match those of ENUM_ORDER_TYPE_FILLING. When I translate SYMBOL_FILLING_MODE to the appropriate ENUM_ORDER_TYPE_FILLING it works.
So in my example using mt5.ORDER_FILLING_IOC successfully closes the position.