Tester-vs-live divergence
Model settings, tick-generation artifacts, spread/slippage assumptions, async order handling, and account-type differences — the classic reasons 'it backtested fine' falls apart live.
Trading Software Development
MQL5 Debugging — Fix an Expert Advisor That Won't Behave
The EA trades differently live than in the tester. The grid forgot its stop-loss. The indicator paints values that vanish on reload. The thing you paid someone else for doesn't match the spec you were given. This is where we live.
NDA by default You own the source code Fixed scope, fixed quote
Overview
What this service actually involves
Debugging engagements start with a diagnosis pass: we reproduce the fault against your logs, chart context, or tester settings, then quote the repair with a fixed price — not an open-ended hourly hunt. If the code is genuinely unfixable (obfuscated, corrupted, or written against a broker behavior that no longer exists), we say so in the diagnosis and quote a rebuild instead.
Compiled .ex5 without source? Sometimes we can rebuild to behavior; often we can't. Send the file and the symptoms during scoping and we'll tell you straight which category you're in before you pay.
Scope
What we fix
Concrete deliverables, not a capability list. Every item below is scoped in writing before a fixed quote is issued.
Order & position logic bugs
Magic-number collisions, partial-close tracking errors, TP/SL modify failures at freeze levels, orphaned orders after disconnects, and money-math mistakes in lot scaling.
Repaint & buffer errors
Indicators whose signals change history, iCustom reads that return EMPTY_VALUE silently, or buffers that break on new-bar vs every-tick recalculation.
Performance problems
EAs that freeze the terminal, indicator loops over full history every tick, and memory leaks in long-running bots.
Compatibility failures
Build/behavior breaks after MT5 updates, broker migration to netting accounts, symbol-spec changes, or DLL/security-settings differences.
Example scopes
Recent example scopes
Anonymized project briefs in the shape real requests arrive — platform, fixed quote, and timeline agreed before work starts.
Netting-account migration fix
MT5 · fixed quote · 4 days
Hedging-designed EA deployed on a netting broker: positions netted against each other and the basket logic double-scaled lots. Diagnosed from logs within a day; reworked position model with per-direction slots and a reconciliation pass on restart.
Repainting entry arrows
MT5 indicator · fixed quote · 3 days
Client's signal indicator rewrote history every new bar — great screenshots, unusable entries. Fixed confirmed-bar calculation, added explicit 'forming' state, and delivered a before/after visual comparison across 3 years of history.
EA stopped trading after broker update
MT4 · fixed quote · 2 days
Broker tightened freeze/stop levels; the EA's SL-set-then-modify pattern began failing silently. Rebuilt order placement with retry classification and alerting so failures surface immediately instead of leaving unprotected positions.
See it work
What it prints to the terminal
A replay of one session's log — the gate decisions, the order build, retcodes, a requote, and a terminal reconnect that rebuilds state from the open ticket. The failure paths are the point.
Strategy tester — terminal log
- 09:14:02.118·OnTick — EURUSD M5, tick 1 of bar
- 09:14:02.118✓session=London spread=11pts limit=18pts PASS
- 09:14:02.119✓ATR(14)=0.00094 band=[0.0006, 0.0021] PASS
A replay of what the EA writes to the terminal — gate checks, sizing arithmetic, retcodes, and the failure paths. Fixed script, not a price feed or a simulated result.
Pricing guidance
Typical project ranges
How budgets map to scope on this service. Your exact fixed quote arrives in writing after a scoping conversation — the numbers below are directional ranges, not promises.
| Scope | Typical range (USD) | Delivery |
|---|---|---|
| Diagnosis + written report | $50 – $150 | 1–3 working days |
| Scoped fix (source available) | $150 – $800 | 2–7 working days |
| Rebuild from compiled-file behavior | quoted as a new build | 1–3 weeks |
Most fixes run $150–$800 after a diagnosis pass (diagnosis itself is $50–$150 and credited toward the repair if you proceed). Rebuilds-from-behavior are quoted as new builds. Fast turnaround is the point — broken automation is bleeding money.
FAQ
Questions traders ask before hiring
Related
Where this goes next
Strategy Optimization & Backtesting
After the fix — prove behavior on real tick data.
Expert Advisor DevelopmentWhen the honest answer is 'rebuild it properly.'
Platform ConversionOld MQL4 codebase causing MQL5 pain? Convert it cleanly.
MT5 DeveloperDeep MQL5 platform expertise behind the fixes.
Delivered by EA debugging specialists. Read about how we work: fixed quotes, milestone demos, source-code ownership, and a 30-day bug-fix window.
Ready to build this?
Book a 30-minute call and bring the strategy, the broken tool, or the rough idea. You leave with a written fixed quote — price, scope, delivery date — before any work starts.
Book a Free Call
A 30-minute call, no obligation. You leave with a written fixed quote — scope, price, delivery date.