MT5 error 10031: No connection with the trade server
Reconnect first: the connection state is in the bottom-right corner of the terminal, and the login and server are under File, Login to Trade Account.
Updated 22 October 2026. Runs in your browser; nothing you type is uploaded.
The number after retcode= in MT5's Experts or Journal tab. 41 codes, as MQL5's reference words them.
What MQL5 says
10031TRADE_RETCODE_CONNECTION- No connection with the trade server
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 terminal is not connected to the broker's trade server: the internet connection dropped, the server name or login is wrong, or the server is down.
The fix in MQL5
Reconnect first: the connection state is in the bottom-right corner of the terminal, and the login and server are under File, Login to Trade Account. An EA can test TerminalInfoInteger(TERMINAL_CONNECTED) and skip sending while it is false.
#include <Trade/Trade.mqh>
CTrade trade;
void OnTick()
{
trade.Buy(0.10, _Symbol);
}#include <Trade/Trade.mqh>
CTrade trade;
void OnTick()
{
if(!TerminalInfoInteger(TERMINAL_CONNECTED))
{
Print("No connection to the trade server; not sending");
return;
}
trade.Buy(0.10, _Symbol);
}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
- MT5 error 10004: Requote
- MT5 error 10006: Request rejected
- MT5 retcode 10009: Request completed
- MT5 error 10013: Invalid request
- MT5 error 10014: Invalid volume in the request
- MT5 error 10015: Invalid price in the request
- MT5 error 10016: Invalid stops in the request
- MT5 error 10017: Trade is disabled
- MT5 error 10018: Market is closed
- MT5 error 10019: There is not enough money to complete the request
- MT5 error 10021: There are no quotes to process the request
- MT5 error 10022: Invalid order expiration date in the request
- MT5 error 10026: Autotrading disabled by server
- MT5 error 10027: Autotrading disabled by client terminal
- MT5 error 10030: Invalid order filling type
- MT5 error 10044: The request is rejected, because the "Only position closing is allowed" rule is set for the symbol
- MT5 error 10046: The request is rejected, because the "Opposite positions on a single symbol are disabled" rule is set for the trading account.
Read a whole MT5 EA's source
- MTR FullSystemEA (MQL5 source) The full MQL5 source of a production MT5 EA for XAUUSD M5 (hedge-grid and recovery): 21 files, 16,923 lines. $49 once.