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MQL5 trade server return code

MQL5 Error 10031: No connection with the trade server

MQL5 error 10031 is TRADE_RETCODE_CONNECTION, the official trade server return code for no connection with the trade server. Pause new sends while TERMINAL_CONNECTED is false, restore the terminal session or network path, then rebuild the request from a fresh quote. Do not queue an unlimited burst for reconnection. 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 10031.mq5
bool TradeConnectionReady()
  {
   if(!(bool)TerminalInfoInteger(TERMINAL_CONNECTED))
     {
      Print("Trade paused: terminal is not connected");
      return false;
     }

   MqlTick tick={};
   return SymbolInfoTick(_Symbol,tick) && tick.time_msc>0;
  }
  • Official code: TRADE_RETCODE_CONNECTION
  • Meaning: No connection with the trade server
  • Layer: trade server response
  • Verify: MqlTradeResult.retcode

What error 10031 actually reports

The code belongs to MqlTradeResult.retcode, not to the compiler error list and not necessarily to GetLastError. The trade server uses 10031 to report no connection with the trade server.

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.

  • Check TERMINAL_CONNECTED and the terminal Journal.
  • Confirm the trading account is logged in to the intended server.
  • Discard stale Bid, Ask, price, and timestamp data after reconnection.
  • Reconcile positions and orders before resuming the EA state machine.

Repair and verify

Pause new sends while TERMINAL_CONNECTED is false, restore the terminal session or network path, then rebuild the request from a fresh quote. Do not queue an unlimited burst for reconnection.

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

This gate requires both a terminal connection and a current symbol tick. A complete EA should also reconcile existing orders and positions after reconnecting.

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 10031.mq5
bool TradeConnectionReady()
  {
   if(!(bool)TerminalInfoInteger(TERMINAL_CONNECTED))
     {
      Print("Trade paused: terminal is not connected");
      return false;
     }

   MqlTick tick={};
   return SymbolInfoTick(_Symbol,tick) && tick.time_msc>0;
  }
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.

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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 10031.

  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

    Pause new sends while TERMINAL_CONNECTED is false, restore the terminal session or network path, then rebuild the request from a fresh quote. Do not queue an unlimited burst for reconnection.

  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 10031 mean?

It is TRADE_RETCODE_CONNECTION, the official MQL5 trade server return code for no connection with the trade server.

Is 10031 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.

Last verified against the linked official references on . 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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