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MQL5 trade server return code

MQL5 Error 10030: Invalid order filling type

MQL5 error 10030 is TRADE_RETCODE_INVALID_FILL, the official trade server return code for invalid order filling type. Read SYMBOL_FILLING_MODE for the symbol and select a permitted filling policy. With CTrade, call SetTypeFillingBySymbol before Buy, Sell, or PositionOpen. Read MqlTradeResult.retcode after OrderSend because a successful function return does not by itself mean that the order was executed.

Open MQL5 Coding AgentReview the diagnostic example

Open the Coding Agent and choose MQL5 from the language menu.

Check retcode 10030.mq5
#include <Trade/Trade.mqh>

CTrade trade;

bool BuyWithSymbolFilling(const string symbol, const double volume)
  {
   if(!trade.SetTypeFillingBySymbol(symbol))
     {
      Print("Cannot select a filling mode for ", symbol);
      return false;
     }

   bool sent=trade.Buy(volume,symbol);
   PrintFormat("sent=%s retcode=%u %s",
               sent ? "true" : "false",
               trade.ResultRetcode(),
               trade.ResultRetcodeDescription());
   return sent;
  }
  • Official code: TRADE_RETCODE_INVALID_FILL
  • Meaning: Invalid order filling type
  • Layer: trade server response
  • Verify: MqlTradeResult.retcode

What error 10030 actually reports

The code belongs to MqlTradeResult.retcode, not to the compiler error list and not necessarily to GetLastError. The trade server uses 10030 to report invalid order filling type.

Keep the request, the boolean returned by OrderSend, result.retcode, result.comment, and the symbol properties in the same log record. That separates a client-side request failure from a server-side rejection.

Inspect the request before changing the strategy

Use the smallest failing order and compare every broker-sensitive value with the current symbol and account. Do not hide the error by retrying unchanged input.

  • Interpret SYMBOL_FILLING_MODE as a flag set, and check the execution-mode rules; do not compare its raw number directly with an ORDER_FILLING enum value.
  • Do not assume that FOK, IOC, or RETURN is accepted for every symbol.
  • If CTrade builds the request, set its filling policy for the current symbol.
  • Log the exact broker symbol because symbol settings are server-specific.

Repair and verify

Read SYMBOL_FILLING_MODE for the symbol and select a permitted filling policy. With CTrade, call SetTypeFillingBySymbol before Buy, Sell, or PositionOpen.

Run OrderCheck with the completed request, log its retcode and comment, then send only if the check is acceptable. OrderCheck improves diagnostics but does not guarantee execution.

Use a focused diagnostic

If called, this helper attempts a real Buy with no SL or TP; use a demo environment and supply separately reviewed volume and risk controls. It selects filling policy from the symbol and logs the retcode, but returns the CTrade boolean rather than confirmed execution. Add an entry point and interpret the retcode and subsequent events before updating position state.

A valid request can still be rejected or filled differently by the trade server. Check the returned retcode, test with the broker symbol and account, and review risk before any live order.

Check retcode 10030.mq5
#include <Trade/Trade.mqh>

CTrade trade;

bool BuyWithSymbolFilling(const string symbol, const double volume)
  {
   if(!trade.SetTypeFillingBySymbol(symbol))
     {
      Print("Cannot select a filling mode for ", symbol);
      return false;
     }

   bool sent=trade.Buy(volume,symbol);
   PrintFormat("sent=%s retcode=%u %s",
               sent ? "true" : "false",
               trade.ResultRetcode(),
               trade.ResultRetcodeDescription());
   return sent;
  }
Where Pineify fits

Repair editable MQL5 source with compiler feedback

Pineify can generate or revise MQL5 source and use MQL5 compilation diagnostics during the coding workflow. Keep the exact error, source location, program type, and intended behavior in the request so the change remains reviewable.

Open MQL5 Coding Agent

Pineify does not run your broker terminal, Strategy Tester, market data, or live orders. Validate the final program in your own MetaTrader 5 environment.

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A practical verification workflow

  1. 1

    Capture the complete result

    Log the OrderSend return value, result.retcode, result.comment, symbol, order type, volume, price, stops, and filling mode. Confirm that the retcode is 10030.

  2. 2

    Read current constraints

    Query the symbol and account immediately before building the request. Broker constraints can differ between symbols and sessions.

  3. 3

    Change the invalid field

    Read SYMBOL_FILLING_MODE for the symbol and select a permitted filling policy. With CTrade, call SetTypeFillingBySymbol before Buy, Sell, or PositionOpen.

  4. 4

    Check, send, and retest

    Call OrderCheck, submit the corrected request, then reproduce it in Strategy Tester and a demo account before considering live use.

Frequently asked questions

What does MQL5 error 10030 mean?

It is TRADE_RETCODE_INVALID_FILL, the official MQL5 trade server return code for invalid order filling type.

Is 10030 a GetLastError code?

Treat it as a trade server return code when it appears in MqlTradeResult.retcode. GetLastError reports the terminal runtime error layer, which is a separate diagnostic channel.

Does OrderSend returning true mean the trade executed?

No. The official OrderSend reference says true means the request passed basic checks and was accepted for processing. Inspect result.retcode and subsequent trade events to determine the outcome.

Check the linked official references for the relevant diagnostic. Compile and test the final source in the MetaTrader 5 build, broker, symbol, and account environment you plan to use.

Continue with reviewable MQL5 source

Provide the exact diagnostic and intended behavior, inspect the generated change, compile it, and verify it in your MT5 test environment.

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