Binance API - 1101 - duplicated value for Symbol parameter - php

Question

I'm trying to call Binance API via PHP code. But I'm getting the following response
{"code":-1101,"msg":"Duplicate values for parameter 'symbol'."}
Even though there is no duplicated value inside the symbol param, its not even an array, here is the code ->
$apiKey = '';
$apiSecret = '';
$url = 'https://api.binance.com/api/v3/order/test';
$data = [
'symbol' => 'BTCUSDT',
'side' => self::SIDE_BUY,
'type' => 'MARKET',
'quantity' => 0.01,
];
$timestamp = time()*1000; //get current timestamp in milliseconds
$query_str = [];
$query_str = $data;
$query_str['timestamp'] = $timestamp;
$query_str = http_build_query($query_str);
$signature = hash_hmac('sha256', $query_str, $apiSecret);
$query_str .= "&signature=" . $signature;
//Decide content type
$content_type = ["Content-Type: application/x-www-form-urlencoded","X-MBX-APIKEY: ".$apiKey];
// Final url
$url .= '?' . $query_str;
$ch = #curl_init();
#curl_setopt($ch, CURLOPT_HEADER, false);
#curl_setopt($ch, CURLOPT_URL, $url);
#curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
#curl_setopt($ch, CURLOPT_HTTPHEADER, $content_type);
#curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 3);
#curl_setopt($ch, CURLOPT_TIMEOUT, 10);
#curl_setopt($ch, CURLOPT_POSTFIELDS, $query_str);
$response = #curl_exec($ch);
$http_code = #curl_getinfo($ch, CURLINFO_HTTP_CODE);
#curl_close($ch);

Answer 1

at the last part of your code you build your final $url, but $url will be separate from other options/parameters... In the way you do it now, symbol and any other parameter will be posted twice.
So remove
$url .= '?' . $query_str;
and the error is gone!
Hope this will work out fine for you.