IBKR-Options-Could-not-find-contract-for-symbol

1. Use IBHistorical.Instance.GetOptionsSymbol() to get the symbol from the option chain instead of OptionSynthetic.GetOptionsSymbol().

2. If you can't use the option chain because you're backtesting with expired contracts (not the case here), you can turn the expired synthetic contract symbol into the IB-formatted symbol like this -

CODE:
   string synSymbol = OptionSynthetic.GetOptionsSymbol(bars, OptionType.Call, bars.LastValue, DateTime.Now);
   WriteToDebugLog(synSymbol);      
   
   // return a string after the first character
   string osym = synSymbol.Substring(1);
   WriteToDebugLog(osym);
   
   //or with  OptionsHelper. The "1" in ConvertSymbol is for IB format
   string osym2 = OptionsHelper.ConvertSymbol(synSymbol, 1);
   WriteToDebugLog(osym2);

Thanks Cone,
using IBHistorical.Instance.GetOptionsSymbol getting correct symbol(QQQ250221C525).
Next step, to get the option bars.

CODE:
//get the option bars
_obars = OptionSynthetic.GetHistory(bars, osym, 0.4);   

_obars are returning !QQQ250221C525

Sure, you're calling OptionSynthetic. For live option data, use GetHistory like for any other symbol.

See the User Guide (F1) > Extensions > Interactive Brokers > Options. There's a TON of information with examples.

Also see the Options blog for even more information with examples for IBHistorical -
https://www.wealth-lab.com/blog/backtest-auto-trade-options

The thing I'll stress here is that IB returns INTRADAY bars only for options. If you need Daily bars, then you need to compress it. Here's another example.

CODE:
using System;
using WealthLab.Backtest;
using WealthLab.Core;
using WealthLab.Data;
using WealthLab.Indicators;
using System.Collections.Generic;
using WealthLab.InteractiveBrokers;

namespace WealthScript21
{
    public class MyStrategy : UserStrategyBase
    {      
      BarHistory _obars;
      
        public override void Initialize(BarHistory bars)
        {
         string osym = IBHistorical.Instance.GetOptionsSymbol(bars, OptionType.Call, bars.LastValue, bars.EndDate, 5);
         
         if (bars.Scale.IsIntraday)
         {
            _obars = GetHistory(bars, osym);
         }
         else  
         {
            // Daily+ , get all the 30min option data from IB
            _obars = GetHistoryUnsynched(osym, HistoryScale.Minute30); 
            if (_obars != null)
            {
               // compress and sync to scale
               _obars = BarHistoryCompressor.ToDaily(_obars);
               _obars = BarHistorySynchronizer.Synchronize(_obars, bars);
            }
         }

         PlotBarHistory(_obars, osym, WLColor.NeonFuschia);          
        }


        public override void Execute(BarHistory bars, int idx)
        {
         // use _obars
      }
    }
}