Troubleshooting Task Exceptions in Reflection-Based Code

A background task can fail while exposing only the message “Exception has been thrown by the target of an invocation.” In this case, reflection invokes Run, so the visible exception describes the invocation boundary rather than the failure inside the method. Log the complete exception object and inspect its nested exception data instead of recording only e.Message.

Identify the Actual Array Failure

The array mass contains 10 elements, but the loop attempts 12 indexed reads. When i reaches the first invalid index, Q = mass[i] throws an exception. Reflection then presents an invocation-level wrapper to the calling delegate.

Capture the Complete Exception

Catch the exception at the task delegate or inside Run, then pass the complete exception object to the application's logging interface. A full exception representation preserves the exception type, stack information, and nested exception details available from the reflection call; the message string alone does not.

Action action = delegate ()
{
    try
    {
        object obj = instance;
        object[] parameters = [];
        MethodInfo mi = type.GetMethod("Run");
        mi.Invoke(obj, parameters);
    }
    catch (Exception e)
    {
        Log(e); // Log the complete exception, not only e.Message.
    }
};

Task task = Task.Factory.StartNew(action);

Log represents the existing application logging interface; the evidence does not specify its implementation. Capturing the exception inside the delegate does not require awaiting the task.

Correct the Loop Boundary

Bind the loop limit to the actual array length so the code remains valid if the array changes. This removes the demonstrated out-of-range access while preserving the existing cycle behavior.

for (int i = 0; i < mass.Length; i++)
{
    Q = mass[i];
    Thread.Sleep(cycle);
}

Verify the Diagnosis and Repair

1. Run the original i < 12 logic and confirm that the logger receives the complete exception object, including the underlying failure details.
2. Change the condition to i < mass.Length and repeat the enabled cycle.
3. Confirm that all 10 elements are read without an array-bound failure and that task termination still follows the existing terminated flag.

FAQ