Runtime Error: 'SPY' wasn't found in the QuoteBars object

#region imports
    using System;
    using System.Collections;
    using System.Collections.Generic;
    using System.Linq;
    using System.Globalization;
    using System.Drawing;
    using QuantConnect;
    using QuantConnect.Algorithm.Framework;
    using QuantConnect.Algorithm.Framework.Selection;
    using QuantConnect.Algorithm.Framework.Alphas;
    using QuantConnect.Algorithm.Framework.Portfolio;
    using QuantConnect.Algorithm.Framework.Execution;
    using QuantConnect.Algorithm.Framework.Risk;
    using QuantConnect.Parameters;
    using QuantConnect.Benchmarks;
    using QuantConnect.Brokerages;
    using QuantConnect.Util;
    using QuantConnect.Interfaces;
    using QuantConnect.Algorithm;
    using QuantConnect.Indicators;
    using QuantConnect.Data;
    using QuantConnect.Data.Consolidators;
    using QuantConnect.Data.Custom;
    using QuantConnect.DataSource;
    using QuantConnect.Data.Fundamental;
    using QuantConnect.Data.Market;
    using QuantConnect.Data.UniverseSelection;
    using QuantConnect.Notifications;
    using QuantConnect.Orders;
    using QuantConnect.Orders.Fees;
    using QuantConnect.Orders.Fills;
    using QuantConnect.Orders.Slippage;
    using QuantConnect.Scheduling;
    using QuantConnect.Securities;
    using QuantConnect.Securities.Equity;
    using QuantConnect.Securities.Future;
    using QuantConnect.Securities.Option;
    using QuantConnect.Securities.Forex;
    using QuantConnect.Securities.Crypto;   
    using QuantConnect.Securities.Interfaces;
    using QuantConnect.Storage;
    using QuantConnect.Data.Custom.AlphaStreams;
    using QCAlgorithmFramework = QuantConnect.Algorithm.QCAlgorithm;
    using QCAlgorithmFrameworkBridge = QuantConnect.Algorithm.QCAlgorithm;
#endregion
namespace QuantConnect.Algorithm.CSharp
{
    public class MeasuredYellowHamster : QCAlgorithm
    {
        int test = 0;
        public override void Initialize()
        {
            SetStartDate(2022, 8, 29);  //Set Start Date
            SetCash(100000);             //Set Strategy Cash
            
            AddEquity("SPY", Resolution.Hour);
            AddEquity("BND", Resolution.Hour);
            AddEquity("AAPL", Resolution.Hour);

        }

        /// OnData event is the primary entry point for your algorithm. Each new data point will be pumped in here.
        /// Slice object keyed by symbol containing the stock data
        public override void OnData(Slice data)
        {
                  if(data.ContainsKey("SPY") && IsMarketOpen("SPY")){
                Debug("TESTING:" + test);
                test++;
                Debug(data.QuoteBars["SPY"].Time.Hour);
            }
            
            if (!Portfolio.Invested)
            {
                SetHoldings("SPY", 0.33);
                SetHoldings("BND", 0.33);
                SetHoldings("AAPL", 0.33);
            }
        }

    }
}

Hey oknoid 

You have to check if the data contains QuoteBars elements:

if(data.QuoteBars.ContainsKey("SPY") && IsMarketOpen("SPY"))

You can read more about QuoteBars here and how to use them.