How To Fix MT5 Error 4756: Unsupported Filling Mode
Your TradingView alert fired, PineConnector received the signal, and then MetaTrader 5 returned error 4756 instead of opening the trade. It is one of the most common errors in automated MT5 trading, and the label it usually carries, unsupported filling mode, points straight at the fix.
This guide explains what 4756 means, how to find the exact reason in your log, and how to clear it, including the PineConnector setting that solves the most common case in one move.
What Error 4756 Actually Means
In MetaTrader 5, error 4756 is ERR_TRADE_SEND_FAILED. It means MT5 tried to send your order to the broker and the broker rejected it, so the order never reached the market.
The key thing to understand is that 4756 is an outer error, not the real reason. It is a wrapper that says the request failed, while the actual cause sits one line away in your log. So the first move is never to change your strategy. It is to read the log.
Step 1: Find the Real Reason in the Log
Open the Toolbox at the bottom of MT5 with Ctrl+T, then check the Journal and Experts tabs. The Experts tab shows what the PineConnector EA tried to do, and the Journal tab shows how the terminal and broker responded. The 4756 line sits in one of these, usually next to the symbol and the time your signal arrived.
Read the few words right after the 4756 code. That phrase is the real problem, and it is almost always one of a short list: unsupported filling mode, no prices, invalid volume, invalid stops, invalid request, or a symbol issue. A line ending in "unsupported filling mode" points straight at the fix below, while "invalid volume" points at your lot size instead.
Once you know which phrase you are dealing with, match it to the right section below. The fix takes seconds.
The Most Common Cause: Unsupported Filling Mode
Every broker accepts orders in a specific filling mode, which is the rule for what happens when an order cannot be filled in full at the requested price. There are three:
- Fill or Kill executes the whole order at once or cancels it entirely.
- Immediate or Cancel fills as much as it can right away and cancels the rest.
- Return keeps the unfilled part of the order live.
Brokers support different modes depending on how they route orders. Market execution accounts, common with ECN and STP brokers, usually expect Fill or Kill or Immediate or Cancel, while instant execution accounts behave differently. If your EA sends a mode your broker does not accept, the broker rejects the order and you get 4756 with "unsupported filling mode" in the log.
PineConnector handles this with a single setting. Open the EA settings with F7 and switch the Broker Set to Broker Set B. That tells the EA to use a filling mode most brokers accept. Resend your signal and the trade should go through. If Broker Set B does not clear it, work through the other Broker Sets, since the right one depends on your broker's execution model.
The Other Things 4756 Can Mean
If the log shows something other than filling mode, use this table. Each reason maps to a fix in your PineConnector EA or your Symbol List.
| Log Reason | How to Fix It |
|---|---|
| No Prices | The symbol is not active in your Symbol List. It enables automatically after this error, so resend the signal. |
| Invalid Request or Trade Disabled | The symbol name does not match your Symbol List exactly. Names are case sensitive, so EURUSD and eurusd are not the same. |
| Invalid Expiration | Switch to Broker Set C in the EA. |
| Invalid Volume | The lot size breaks your broker's rules. Check the symbol's volume step and minimum in the Symbol List. |
| Invalid Stops | Your stop or target is too close to price. Use a pips or percentage target type in the EA, or widen the values. |
| Invalid Price | Your stop, target, or pending entry price is too close or invalid, such as a stop set beyond the take profit. Use pips based targets and larger values. |
| Requote Detected | Common on the MetaQuotes demo server, which has strict execution rules. Move to a reputable live broker. |
How to Avoid 4756 in the First Place
A few setup habits stop 4756 from appearing at all:
- Set the correct Broker Set during setup, not after the first failed trade.
- Use pips or percentage target types rather than price, since TradingView and broker quotes differ. The PineConnector syntax guide covers the options.
- Confirm your symbol names with Symbol Mapping so every alert uses your broker's exact ticker.
- Test on a demo account before going live, so you catch a filling mode or symbol mismatch with no money at stake.
Most 4756 errors come down to one broker specific setting, and once your Broker Set and symbols are right, they stop appearing. For the full list of MetaTrader codes and fixes, see our common MetaTrader errors guide or the PineConnector error guide.
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