Execution quality after a platform update: a before/after sample

[FXS London Scalper]

Platform updates (a new MT5 build, a cTrader version, a broker's server migration) occasionally change execution behaviour. Usually it's fine. Sometimes it isn't, and nobody notices until weeks later.

A simple before/after check:

1. Before the update, note your recent averages: entry slippage, stop slippage, reject rate, order-to-fill time from the Journal. Use the last 50–100 trades.
2. After the update, collect the same metrics for the next 50–100 trades.
3. Compare. Look for meaningful shifts, not small noise.

What might change:
- Order-to-fill time, if the update changed how orders are routed.
- Reject or requote behaviour.
- Slippage tolerance defaults on order tickets.
- Behaviour of EAs, if functions changed.

Also check settings after updates: some reset defaults, such as one-click trading or maximum deviation.

It's a small effort. If something did change, you'll have the numbers to raise it with support.

Has an update ever changed your execution noticeably?

[Shadow Trader]

A broker releases a new platform build. The terminal prompts for an update. Clicking yes during a session can lose chart settings, break custom indicators or change behaviour of automated scripts.

The risk is not theoretical. Updates have changed how some indicators calculate, how timestamps are displayed, and how orders are validated. A script that ran for months can misbehave after a silent update.

A sensible habit is delaying updates until a weekend and testing on a demo version before using the new one live. A copy of the old installation, with its data folder, provides a way back.

Release notes sometimes mention changes that matter, such as new order handling rules or altered default settings.

Keeping a changelog of the platform build number alongside the trade journal helps. If results shift at a specific date, the build number may explain it.

Has a platform update ever changed trading behaviour without warning?