---
name: mql5-ea-troubleshooting
description: MQL5 EA runtime errors and attach failures — init failures, INVALID_HANDLE 32757, build-specific enum differences
---

# MQL5 EA Troubleshooting

## Common runtime errors (attach failed)

### Error 32757 (0x8001 = E_HANDLE / INVALID_HANDLE)
Usually means an indicator handle creation failed, or a **function call/argument mismatch** in `OnInit()`.

**Stack mismatch diagnosis:**
```mql5
// Call site passes 9 args:
g_orderManager.Init(g_symbol, InputMagicNumber, InputComment,
                    InputEntryPrice, InputSL, InputTP,
                    InputMaxFollowOrders, InputUseTrailingSL,
                    InputFollowDelayBars);  // ← 9 args

// But declaration only accepts 8:
void Init(string symbol, int magicNumber, string comment,
          double inputEntry, double inputSL, double inputTP,
          int maxFollow, bool useTrailing, int followDelayBars);  // ← 8 params
//                                                                                         ↑ stack corrupted
```
Fix: match declaration to call.

**Indicator handle failure:**
- `iATR(symbol, PERIOD_M5)` → in some builds requires 3 params: `iATR(symbol, PERIOD_M5, period)`
- `iATR(handle)` returns `INVALID_HANDLE` if symbol/timeframe unavailable
- Always check: `if(handle == INVALID_HANDLE) return INIT_FAILED;`

---

## Build-specific enums (tested on build 3570+)

| Enum | Wrong | Correct |
|------|-------|---------|
| ATR params | `iATR(sym, TF)` (2 args) | `iATR(sym, TF, period)` (3 args) |
| Account margin | `ACCOUNT_MARGIN_MODE_NETTING` | `ACCOUNT_MARGIN_MODE_RETAIL_NET` |
| Account free margin | `ACCOUNT_FREEMARGIN` (deprecated) | `ACCOUNT_MARGIN_FREE` |
| Symbol contract size | `SYMBOL_CONTRACT_SIZE` | `SYMBOL_TRADE_CONTRACT_SIZE` |
| Margin rate | `SYMBOL_MARGIN_RATE` (doesn't exist) | `SYMBOL_MARGIN_HEDGED` or use `OrderCalcMargin()` |
| TRADE_TRANSACTION | `TRADE_TRANSACTION_POSITION_CLOSE`, `_OPEN` don't exist | Use `TRADE_TRANSACTION_DEAL_ADD` + `TRADE_TRANSACTION_POSITION` |
| `CTrade.SetComment()` | doesn't exist | Pass comment string directly to `Buy()`/`Sell()` |

---

## Type coercion warnings (benign — still compile)
- `SymbolInfoInteger()` returns `long`; assign to `double` with explicit cast: `(double)SymbolInfoInteger(sym, SYMBOL_SPREAD)`
- `rates[].tick_volume` is `long`; cast: `(double)rates[0].tick_volume`

---

## Debug approach for attach/init failures

1. Check if error is an `INIT_*` code ( INIT_PARAMETERS_INCORRECT = 5, INIT_FAILED = 7)
2. If not INIT code → look for INVALID_HANDLE or E_HANDLE
3. Search all files for `IndicatorCreate`, `iATR`, `iAC`, `iADX` — ensure all handles checked
4. Count arguments in every Init/constructor call vs. declaration
5. Check global-scope code that runs before `OnInit()` (including class member constructors)
