OrderSend Error 129 in MT4/MQL4: Invalid Price Fix

OrderSend Error 129 in MT4/MQL4 means that the order price is invalid. In most cases, this error occurs when the price passed to OrderSend() does not match the current Bid/Ask price or the broker’s order rules.

This error is commonly shown as Invalid Price. It often happens when an EA uses the wrong price for Buy or Sell orders, sends an old price, or uses a pending order price on the wrong side of the market.

What Does OrderSend Error 129 Mean?

In MQL4, Error 129 is known as:

• Error code: 129
• Error name: ERR_INVALID_PRICE
• Meaning: Invalid price

This means that the price value passed to OrderSend() is not accepted by MT4 or the broker server.

OrderSend(Symbol(), OP_BUY, Lots, price, Slippage, StopLoss, TakeProfit, "buy order", Magic, 0, clrBlue);

If price is wrong, outdated, not normalized, or not valid for the order type, MT4 may return Error 129 and the order will not be placed.

Common Causes of OrderSend Error 129

Correct Price for Buy and Sell Orders

For market orders, the price must match the order type.

A Buy order should be opened at the Ask price.

RefreshRates();

double price = NormalizeDouble(Ask, Digits);

int ticket = OrderSend(
    Symbol(),
    OP_BUY,
    Lots,
    price,
    Slippage,
    0,
    0,
    "buy order",
    Magic,
    0,
    clrBlue
);

if(ticket < 0)
{
    Print("OrderSend failed. Error: ", GetLastError());
}

A Sell order should be opened at the Bid price.

RefreshRates();

double price = NormalizeDouble(Bid, Digits);

int ticket = OrderSend(
    Symbol(),
    OP_SELL,
    Lots,
    price,
    Slippage,
    0,
    0,
    "sell order",
    Magic,
    0,
    clrRed
);

if(ticket < 0)
{
    Print("OrderSend failed. Error: ", GetLastError());
}

Use RefreshRates Before OrderSend

Error 129 can occur when the EA uses an old price. Before sending an order, call RefreshRates() to update Bid and Ask.

RefreshRates();

double buyPrice  = NormalizeDouble(Ask, Digits);
double sellPrice = NormalizeDouble(Bid, Digits);

Print("Bid: ", Bid);
Print("Ask: ", Ask);
Print("Buy price: ", buyPrice);
Print("Sell price: ", sellPrice);

This is especially important when the EA performs several calculations before calling OrderSend(). The longer the delay between price calculation and order execution, the more likely the price may become outdated.

Normalize Price with NormalizeDouble

Another common cause of Error 129 is a price with invalid decimal digits. Use NormalizeDouble(price, Digits) before sending the price to OrderSend().

double price = Ask;

// Normalize the price according to the symbol digits
price = NormalizeDouble(price, Digits);

This is also important for stop loss, take profit, and pending order prices.

RefreshRates();

double price = NormalizeDouble(Ask, Digits);
double sl    = NormalizeDouble(Bid - 100 * Point, Digits);
double tp    = NormalizeDouble(Bid + 100 * Point, Digits);

Pending Orders Can Also Cause Error 129

Pending order prices must be placed on the correct side of the current market price. If the pending order price is logically invalid, OrderSend() may fail.

For example, a Buy Limit should be placed below the current Ask price.

RefreshRates();

double price = Ask - 100 * Point; // Buy Limit below Ask
price = NormalizeDouble(price, Digits);

int ticket = OrderSend(
    Symbol(),
    OP_BUYLIMIT,
    Lots,
    price,
    Slippage,
    0,
    0,
    "buy limit",
    Magic,
    0,
    clrBlue
);

if(ticket < 0)
{
    Print("OrderSend failed. Error: ", GetLastError());
}

MQL4 Code Example: Check Pending Order Price Direction

The following function checks whether the pending order price is on the correct side of the current price.

//+------------------------------------------------------------------+
//| Check whether pending order price direction is valid             |
//+------------------------------------------------------------------+
bool IsPendingPriceDirectionValid(int orderType, double price)
{
    RefreshRates();

    price = NormalizeDouble(price, Digits);

    if(orderType == OP_BUYLIMIT)
        return price < Ask;

    if(orderType == OP_BUYSTOP)
        return price > Ask;

    if(orderType == OP_SELLLIMIT)
        return price > Bid;

    if(orderType == OP_SELLSTOP)
        return price < Bid;

    return false;
}

Usage example:

RefreshRates();

double price = Ask - 100 * Point;
price = NormalizeDouble(price, Digits);

if(!IsPendingPriceDirectionValid(OP_BUYLIMIT, price))
{
    Print("Invalid pending order price direction.");
    return;
}

int ticket = OrderSend(
    Symbol(),
    OP_BUYLIMIT,
    Lots,
    price,
    Slippage,
    0,
    0,
    "buy limit",
    Magic,
    0,
    clrBlue
);

if(ticket < 0)
{
    Print("OrderSend failed. Error: ", GetLastError());
}

This check helps prevent invalid pending order prices before the EA sends the order.

MQL4 Code Example: Get Correct Market Order Price

For market orders, you can use a helper function to return the correct price based on the order type.

//+------------------------------------------------------------------+
//| Get correct market order price                                   |
//+------------------------------------------------------------------+
double GetMarketOrderPrice(int orderType)
{
    RefreshRates();

    if(orderType == OP_BUY)
        return NormalizeDouble(Ask, Digits);

    if(orderType == OP_SELL)
        return NormalizeDouble(Bid, Digits);

    return 0;
}

Usage example:

int orderType = OP_BUY;
double price = GetMarketOrderPrice(orderType);

if(price <= 0)
{
    Print("Invalid order type.");
    return;
}

int ticket = OrderSend(
    Symbol(),
    orderType,
    Lots,
    price,
    Slippage,
    0,
    0,
    "market order",
    Magic,
    0,
    clrBlue
);

if(ticket < 0)
{
    Print("OrderSend failed. Error: ", GetLastError(), " Price: ", price);
}

How to Debug OrderSend Error 129

When Error 129 occurs, print the order type, Bid, Ask, price, and Digits. This makes it much easier to identify why the order price was rejected.

RefreshRates();

Print("Order type: ", OrderType);
Print("Bid: ", Bid);
Print("Ask: ", Ask);
Print("Price used: ", Price);
Print("Digits: ", Digits);
Print("Point: ", Point);
Print("Normalized price: ", NormalizeDouble(Price, Digits));

Then check the Experts tab or the Journal tab in MT4. If the EA used Bid for a Buy order, Ask for a Sell order, or an old price, that is likely the reason for Error 129.

Error 129 vs Error 130

Error 129 and Error 130 are often confused because both are related to order prices. However, the meaning is different.

If the market order uses the wrong Bid/Ask price, check Error 129. If the stop loss, take profit, or pending order price is too close to the current price, check Error 130.

Related MQL4 Errors

OrderSend Error 129 is one of several common OrderSend errors in MT4. The table below shows related errors that are often checked together.

FAQ About OrderSend Error 129

Summary

OrderSend Error 129 in MT4/MQL4 means that the order price is invalid. In most cases, the EA is using the wrong Bid/Ask price, an outdated price, a non-normalized price, or an invalid pending order price.

• Error 129 is ERR_INVALID_PRICE.
• Use Ask for Buy market orders.
• Use Bid for Sell market orders.
• Call RefreshRates() before OrderSend().
• Use NormalizeDouble(price, Digits) for order prices.
• Check the correct price direction for pending orders.
• If the problem is related to SL, TP, or stop distance, check OrderSend Error 130 instead.

If your EA returns Error 129, start by printing Bid, Ask, the order type, and the price passed to OrderSend(). Understanding which price was rejected is the fastest way to fix the EA and avoid repeated order failures.

Related: OrderSend Error 130 in MT4/MQL4

Related: OrderSend Error 131 in MT4/MQL4

Related: OrderSend Error 134 in MT4/MQL4

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