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MetaTrader error codes / MT4 trade server errors

MT4 error 3: Invalid trade parameters (ERR_INVALID_TRADE_PARAMETERS)

The trade function got parameters that don't make sense, such as a wrong order type or a bad ticket. Nothing was executed.

3ERR_INVALID_TRADE_PARAMETERS
After a fixSafe to retry?
NoCould it have executed?

What it means

You see this code in GetLastError() in MQL4, after a trade function fails on the server side.

Error 3 means the arguments to the trade function don't form a valid request. The server or terminal refused it as written.

It is usually a bug in how the request was built, not a market condition.

Common causes

  • An order type that doesn't match the price, such as OP_BUY with the Bid.
  • OrderClose() on a pending order. Pending orders need OrderDelete().
  • A negative or zero lot size, or a negative slippage.
  • A ticket that belongs to another symbol or account.

How to fix it

  • Buy at Ask, sell at Bid, and close a buy at Bid and a sell at Ask.
  • Use OrderDelete() for pending orders and OrderClose() for market orders.
  • Print every argument before the call while you debug.

Example in MQL4:

if(OrderSelect(ticket, SELECT_BY_TICKET))
{
   bool ok;
   if(OrderType() == OP_BUY)
      ok = OrderClose(ticket, OrderLots(), Bid, 3);
   else if(OrderType() == OP_SELL)
      ok = OrderClose(ticket, OrderLots(), Ask, 3);
   else
      ok = OrderDelete(ticket);          // pending orders are deleted
   if(!ok) Print("failed, error ", GetLastError());
}

Is it safe to retry?

After you fix the parameters.

Could the order have executed?

No. The request was invalid.

How Tickwire handles it

Tickwire treats it like MT5 10013, and the MT4 code stays in the message. See trade results.

All MetaTrader error codes

One API for MT4 and MT5

Clear trade outcomes, idempotent orders and an audit log. Read the error reference or the quickstart.

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