MQL5 error 4752: trading by Expert Advisors prohibited

What it means

GetLastError() says that this program isn't allowed to trade. The trade function didn't fail because of the order itself; trading is blocked somewhere between the terminal, the EA's settings and the account. In MetaTrader 4 the same situation was error 4109.

Usual causes

MetaQuotes' reference lists four levels of permission, and any one of them blocks trading:

• The terminal. The Algo Trading button in the toolbar is off. The order shows retcode 10027.
• The program. "Allow Algo Trading" isn't ticked in the EA's Common tab.
• Automated trading for the account. The broker has disabled Expert Advisors on the account (ACCOUNT_TRADE_EXPERT is false).
• Trading for the account. ACCOUNT_TRADE_ALLOWED is false: no connection to the server, an account that was archived or switched to read-only, trading disabled by the broker, or a login with the investor password.

How to detect it

• GetLastError() returns 4752 after a trade function. Depending on where the block happens, the result's retcode can also show 10027.
• Check the four properties in code: TerminalInfoInteger(TERMINAL_TRADE_ALLOWED), MQLInfoInteger(MQL_TRADE_ALLOWED), AccountInfoInteger(ACCOUNT_TRADE_EXPERT) and AccountInfoInteger(ACCOUNT_TRADE_ALLOWED).
• With the investor password, the terminal's journal records that trading has been disabled in investor mode.

Broken code

This EA compiles. When trading is blocked it prints 4752 on every tick and leaves you to guess which of the four permissions is missing.

#include <Trade/Trade.mqh>

CTrade trade;

void OnTick()
  {
   if(PositionSelect(_Symbol))
      return;
   if(!trade.Buy(0.10))
      Print("Buy failed, error ", GetLastError());   // "4752", and nothing about which switch is off
  }

Fixed code

The same program with the check that prevents the error. It compiles in MetaEditor with 0 errors and 0 warnings.

#include <Trade/Trade.mqh>

CTrade trade;

// Empty string when the EA may trade, otherwise the first permission that's missing
string TradeBlockedReason()
  {
   if(!TerminalInfoInteger(TERMINAL_CONNECTED))
      return "no connection to the trade server";
   if(!TerminalInfoInteger(TERMINAL_TRADE_ALLOWED))
      return "Algo Trading is off in the terminal's toolbar";
   if(!MQLInfoInteger(MQL_TRADE_ALLOWED))
      return "Allow Algo Trading is not ticked in this EA's Common tab";
   if(!AccountInfoInteger(ACCOUNT_TRADE_EXPERT))
      return "the broker has disabled Expert Advisors on this account";
   if(!AccountInfoInteger(ACCOUNT_TRADE_ALLOWED))
      return "the account can't trade (investor password, read-only or disabled)";
   return "";
  }

void OnTick()
  {
   static string lastReason = "";
   string reason = TradeBlockedReason();
   if(reason != lastReason)
     {
      Print(reason == "" ? "Trading allowed" : "Trading blocked: " + reason);
      lastReason = reason;
     }
   if(reason != "" || PositionSelect(_Symbol))
      return;
   ResetLastError();
   if(!trade.Buy(0.10))
      PrintFormat("Buy failed: error %d, retcode %u (%s)", GetLastError(), trade.ResultRetcode(), trade.ResultRetcodeDescription());
  }

Why the fix works

TradeBlockedReason() runs the checks from MetaQuotes' "Trade permission" page in order, plus the connection, and returns a sentence naming the first one that fails. The EA logs the reason once when it changes, not on every tick, and doesn't send orders while trading is blocked. When it does trade and fail, it logs both numbers: GetLastError() and the retcode.

Questions

The programs on this page are minimal examples written to show the error and its fix, not trading systems. Some of them send orders when they run: try them on a demo account. Trading involves substantial risk of loss and is not suitable for every investor. Edgoro is a software tool, not a broker or financial adviser: nothing it produces is investment advice, and past or backtested performance does not guarantee future results.