MT4/MQL4 Technical Notes

Learn how to structure reusable MQL4 order functions for MT4 EAs, including OrderSend, OrderModify, OrderClose, retry handling, spread checks, and error debugging.

Learn why Error 129 occurs in MT4 and how to fix invalid price errors by checking Bid, Ask, RefreshRates, NormalizeDouble, and pending order prices.

Learn why Error 130 occurs in MT4 and how to fix invalid stops by checking StopLevel, stop loss, take profit, pending orders, and broker rules.

Learn why Error 131 occurs in MT4 and how to check lot size, minimum lot, lot step, maximum lot, and broker settings.

Learn why Error 134 occurs in MT4 and how to fix not enough money errors by checking free margin, lot size, leverage, margin requirements, and account balance.

Fix common MT4 Strategy Tester problems, including no trades, wrong settings, missing historical data, optimization issues, and EA conditions that never trigger.

Learn how to prepare Dukascopy historical data for MT4 EA backtesting, including data import, timeframe preparation, time zone differences, and common mistakes.

Learn how to use Quant Analyzer to analyze MT4 backtest reports, review hourly and monthly performance, sort trades, and find weaknesses in your EA.