How to Fix Binance API Error -1102 (Mandatory Parameter Missing/Malformed) – 2026 Webhook Guide

If you are running algorithmic strategies by connecting TradingView Webhooks to a custom Python server or directly to the Binance API, Error -1102 is your worst enemy.

Your chart prints a perfect “Buy” signal, the webhook fires, but your exchange log spits back: Error -1102: A mandatory parameter (symbol/side/type) was not sent, was empty/null, or malformed.

The signal was correct, but the execution failed. Here is the 2026 technical guide to fixing your JSON payloads and Webhook formatting so you never miss a trade again.

Step 1: Fix the TradingView JSON Payload Formatting

The most common cause of Error -1102 is invalid JSON syntax sent from TradingView’s alert message box. Binance’s API requires strict parsing.

1. The Issue: Using single quotes (') instead of double quotes ("), or trailing commas in your JSON payload.
2. The Fix: Open your TradingView Alert settings. Ensure your message looks exactly like this, with strict double quotes: { "symbol": "{{ticker}}", "side": "BUY", "qty": "{{strategy.order.contracts}}" }
3. Hidden Trap: If {{ticker}} outputs something like BINANCE:BTCUSDT, the API will reject it. You must ensure your script formats the symbol precisely as BTCUSDT without the exchange prefix.

Step 2: Handle String-to-Float Conversion in Python/CCXT

If you are using a Python middleware (Flask/FastAPI) to catch the webhook before sending it to CCXT, the qty or price parameters might be passed as strings instead of floats.

• Wrong: exchange.create_order(symbol, 'limit', 'buy', "1.5", "65000")
• Right: You must cast the payload values to the correct data type before execution: quantity = float(request_data['qty']) price = float(request_data['price'])

Step 3: Verify the “Content-Type” Header

If Binance tells you all mandatory parameters are missing, it means the API engine didn’t parse your body payload at all.

1. The Check: Ensure your HTTP request headers explicitly define the payload format.
2. The Fix: You must include 'Content-Type': 'application/json' or 'Content-Type': 'application/x-www-form-urlencoded' depending on the specific endpoint you are hitting. (REST v3 typically requires URL-encoded parameters, not raw JSON body).

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