How to add an Expert Advisor to MT5

1. 1

   Check what file you have

   MT5 runs .ex5 files (compiled) and compiles .mq5 files (source). .ex4 and .mq4 files are for MetaTrader 4 and won't run in MT5 — see converting an MT4 EA.
2. 2

   Copy it into the Experts folder

   In MT5 go to File → Open Data Folder, then open MQL5 → Experts and paste the file there. Using the Data Folder menu matters: MT5 often keeps its files somewhere other than its install folder.
3. 3

   Compile it (for .mq5 files)

   Open the file in MetaEditor (press F4 in MT5, then open it) and press F7 or click Compile. The Errors tab at the bottom should say 0 errors; that creates the .ex5 file MT5 actually runs. An .ex5 file skips this step.
4. 4

   Refresh the Navigator

   Back in MT5, open the Navigator (Ctrl+N), right-click Expert Advisors and choose Refresh. Your EA appears in the list.
5. 5

   Attach it to the right chart

   Open a chart of the symbol and timeframe the EA was built for, then drag the EA from the Navigator onto the chart (or double-click it).
6. 6

   Allow Algo Trading and set its inputs

   In the window that opens, tick Allow Algo Trading on the Common tab, review the settings on the Inputs tab (lot size, stops, and so on), then click OK.
7. 7

   Turn on Algo Trading in the toolbar

   Click the Algo Trading button in MT5's main toolbar so it's switched on. Without it, no EA on any chart can place trades, even with the box ticked in step 6.
8. 8

   Check the Experts and Journal tabs

   Open the Toolbox (Ctrl+T). The Experts tab shows messages from the EA itself; the Journal shows platform errors such as rejected orders.

1. 1

   It's not in the Navigator

   The file is in the wrong folder (use File → Open Data Folder), an .mq5 file hasn't been compiled, or the list needs a Refresh.
2. 2

   It's attached but never trades

   Check the Algo Trading button, whether the market is open, and whether the EA's conditions have actually occurred yet. A rules-based EA can go days without a signal.
3. 3

   Orders get rejected

   The Journal tab says why. Common causes: a lot size below your broker's minimum, stops too close to price, or an account that doesn't allow automated trading.
4. 4

   It stops when you close MT5

   An EA only runs while MT5 is open and connected. To keep it trading around the clock, run MT5 on a VPS.

Run any new EA on a demo account first, and ideally through MT5's Strategy Tester before that. How to backtest an EA in MT5 walks through it.