How to find
MetaTrader's log files
There are two sets of logs and they answer different questions. The Journal is the terminal talking to your broker. The Experts log is your EA talking to itself. Sending the wrong one is the most common reason a support ticket takes an extra day.
Open the data folder
In MetaTrader, click File then Open Data Folder, or press Alt + F then D. A Windows folder opens. This is not where MetaTrader is installed — it is where it keeps your settings and logs, and the two are in different places.
For connection problems, open logs
The logs folder in that window holds what you see in the terminal's Journal tab: logins, disconnections, order rejections from the broker. One file per day, named by date.
For EA problems, open MQL4 then Logs
Go into MQL4 and then Logs inside it. That is the Experts tab: what your EA printed, what it decided, and any error it hit. On MT5 the folder is MQL5.
Send us the right day
Log files are named by date, so pick the day the problem happened. Both files if you are not sure — they are small, and it saves us asking.
Reading them, and other questions
Which one do I need?
If the platform disconnected, could not log in, or an order was rejected, that is logs. If an EA did not open a trade you expected, that is MQL4/Logs. If you cannot tell, send both.
The folder is empty
You are looking at a fresh install, or logs were cleared. MetaTrader writes them as it runs, so reproduce the problem and look again.
The files will not open
They are plain text with a .log extension. Right-click, Open with, Notepad. On a busy terminal they can be large — Notepad copes, but Notepad++ is easier to read.
I cannot find the data folder at all
The menu path is the reliable way. Browsing to Program Files finds the installation rather than the data, and the logs are not there.
What should I look for myself?
Lines with failed, rejected, invalid or no connection. An EA that stopped trading usually printed a reason just before it stopped.