Access violation reading location 0xFFFFFFFFFFFFFFFF

Thanks for your advices, I'm following the option of Race Condition because I run many threads in that phase, so I'm trying to run this problematic procedure in a different thread.
Do you know how I can be sure that my code is thread-safe?

As requested, here is the step-by-step guide to ensure thread safety and troubleshoot race conditions:

Checklist:

• Identify shared resources accessed by multiple threads.
• Use synchronization primitives (lock, Monitor, Mutex) for critical sections.
• Prefer thread-safe collections like ConcurrentDictionary and ConcurrentQueue.
• Avoid static mutable state; use thread-local storage.
• Use Interlocked for atomic operations.
• Validate unmanaged code for thread safety or wrap calls in locks.
• Perform stress tests using Visual Studio Concurrency Visualizer.
  Sample Code:

    private readonly object locker = new object();
    private int sharedCounter = 0;
    
    public void SafeIncrement()
    {
        lock (locker)
        {
            sharedCounter++;
        }
    }
    
    // Alternative using Interlocked
    public void SafeIncrementAtomic()
    {
        Interlocked.Increment(ref sharedCounter);
    }
    ``
  

  Let me know if the issue persists after following these steps. I’ll be happy to assist further if needed. If the issue has been resolved, please click "Accept Answer".

Thanks for your reply, I'll check my code regarding the thread-safe

Hope you're doing well! Please let us know if the issue persists or resolved. If the answer is helpful, Kindly mark the provided solution as "Accept Answer", so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated. If we didn't get any response from your side. we will proceed to close the thread by October 30th.

Hi. The issue unfortunately persists but your advices have been very useful. Maybe I have a problem of Race conditions but, in my opinion, not only this. I changed that part of the code a lot but without solving it. I'm investigating what else might be wrong, that's why I didn't respond before.