MT5 error 4109: trade not allowed.

1. Turn on AutoTrading (the green button)

Fixes cause 1 — the most common by far. The AutoTrading button in the MT5 toolbar must be green. If it is red or grey, every order from every EA and script is rejected with 4109 before it even reaches the broker.

• Look at the toolbar, top of the terminal: the AutoTrading button (a play icon) must show green.
• Or press Ctrl+E to toggle it.
• Check the chart’s top-right corner: the EA icon must be a smiley, not a sad face.

2. Allow algorithmic trading (global + per-EA)

Fixes cause 2. There are two separate checkboxes and both must be on — this is why manual trading can work while the EA still gets 4109.

• Global: Tools > Options > Expert Advisors > tick Allow algorithmic trading. Press OK.
• Per-EA: right-click the chart with your EA > Expert Advisors > Properties (or press F7) > Common tab > tick Allow algorithmic trading.
• Re-check the chart icon: smiley = allowed to trade.

Heads up: changing the chart’s symbol or timeframe re-attaches the EA and can silently reset the per-EA checkbox on some builds — if 4109 comes back after touching the chart, look here first.

3. Check the symbol is actually open for trading

Fixes cause 3. If 4109 only happens on one symbol, open Ctrl+U (Symbols), select it and check its Specification: the Trade field must say Full. Close-only means you can only exit positions; Disabled means the broker turned it off.

• Press Ctrl+U, find the symbol, open Specification and read the Trade mode.
• Check the sessions: many symbols (indices, metals, prop-firm symbols) stop quoting outside their hours — orders then return 4109.
• Weekend or broker holiday? Wait for the session to reopen, or test on a 24/7 symbol like a crypto CFD.

4. Rule out a read-only or restricted account

Fixes cause 4. If you logged in with the investor password, MT5 lets you watch everything but rejects every order with 4109 — the terminal looks completely normal otherwise.

• Log out and log back in with the master password (not the investor one) via File > Login to Trade Account.
• Try a manual trade on a liquid symbol. If manual trading is also rejected, the restriction is on the account, not on your setup — talk to your broker or prop firm.
• On prop-firm accounts, check for news or weekend trading restrictions — some firms disable trading around high-impact events.

5. Fixing 4752: validate the order parameters

Fixes causes 5 and 6. Error 4752 means the request itself is malformed — the terminal is on, the symbol is open, but the numbers do not fit the broker’s contract. Open the symbol’s Specification (Ctrl+U) and compare against what your EA or alert is sending:

• Volume: normalize the lot to the symbol’s volume step and keep it between minimal and maximal volume. Sending 0.001 on a symbol with a 0.01 step = invalid request.
• Price: never send price 0 on a pending order — use a real price, or send a market order if you want immediate execution.
• Order type: confirm the symbol supports what you are sending (buy/sell vs pending types) and that SL/TP respect the broker’s stops level distance.

The alert or webhook payload

If you trade from TradingView alerts, the 4752 you see in the Experts tab is often born in the JSON of the alert message, not in MT5: a "lot" with decimals your broker rejects, an empty "price", or a field with a typo. The terminal only reports what it received. Paste your exact payload into our free webhook tester and compare it against the field schema in the docs before touching anything else.

The EA configuration

EA inputs can produce both errors: a risk-percent sizing rule that computes a lot below the broker’s minimum (4752), or an SL/TP override too close to the price for the symbol’s stops level. Open the EA properties (F7) and check the effective values — and if you use remote settings from a dashboard, remember they overwrite the local inputs on every sync.