MT5 error 10030: Invalid order filling type

Choose Fill or Kill or Immediate or Cancel from the symbol's SYMBOL_FILLING_MODE flags, and Return otherwise.

Updated 22 October 2026. Runs in your browser; nothing you type is uploaded.

Return code or words from the message

The number after retcode= in MT5's Experts or Journal tab. 41 codes, as MQL5's reference words them.

10030

TRADE_RETCODE_INVALID_FILL

Invalid order filling type

Cause and fix for 10030

What MQL5 says

10030 TRADE_RETCODE_INVALID_FILL: Invalid order filling type

From MQL5's table of trade server return codes, read 22 October 2026. An Expert Advisor finds it in MqlTradeResult.retcode; the Experts and Journal tabs print it.

What causes it

The order's type_filling (FOK, IOC or RETURN) is one the symbol does not allow; read SYMBOL_FILLING_MODE instead of hard-coding it.

The fix in MQL5

Choose Fill or Kill or Immediate or Cancel from the symbol's SYMBOL_FILLING_MODE flags, and Return otherwise; MQL5 allows Return in every execution mode except Market execution. CTrade's Buy() and Sell() make this choice themselves on Market-execution symbols, so 10030 mostly comes from requests built by hand.

Before

void OpenBuy(const double lots)
  {
   MqlTradeRequest req = {};
   MqlTradeResult  res = {};
   req.action       = TRADE_ACTION_DEAL;
   req.symbol       = _Symbol;
   req.volume       = lots;
   req.type         = ORDER_TYPE_BUY;
   req.price        = SymbolInfoDouble(_Symbol, SYMBOL_ASK);
   req.type_filling = ORDER_FILLING_FOK;     // hard-coded: this broker's symbol may not list it
   if(!OrderSend(req, res))
      Print("OrderSend failed: ", res.retcode);
  }

After

ENUM_ORDER_TYPE_FILLING FillingFor(const string symbol)
  {
   const long modes = SymbolInfoInteger(symbol, SYMBOL_FILLING_MODE);
   if((modes & SYMBOL_FILLING_FOK) == SYMBOL_FILLING_FOK)
      return(ORDER_FILLING_FOK);
   if((modes & SYMBOL_FILLING_IOC) == SYMBOL_FILLING_IOC)
      return(ORDER_FILLING_IOC);
   return(ORDER_FILLING_RETURN);              // allowed in every mode except Market execution
  }

void OpenBuy(const double lots)
  {
   MqlTradeRequest req = {};
   MqlTradeResult  res = {};
   req.action       = TRADE_ACTION_DEAL;
   req.symbol       = _Symbol;
   req.volume       = lots;
   req.type         = ORDER_TYPE_BUY;
   req.price        = SymbolInfoDouble(_Symbol, SYMBOL_ASK);
   req.type_filling = FillingFor(_Symbol);
   if(!OrderSend(req, res))
      Print("OrderSend failed: ", res.retcode, " ", res.comment);
  }

Both compile in MetaEditor 5 with no errors or warnings. Adapt them to your EA; they were not run against a trade server.

Other MT5 errors

Method and privacy

Method: The constant and the description are MQL5's reference table of trade server return codes, read 22 October 2026. The MQL5 code compiles in MetaEditor 5 with no errors or warnings; it is an example to adapt and was not run against a trade server.

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