With an ASP.NET MVC controller, I call a function runPreflighter that runs a task. This task loops on a set of given files, runs them through an external rest API, reads a log file, and updates a database with the the results.

Occasionally, the task fails silently, and calls update the database with the error/emails to send to users with the error do not complete.

Running the same files later on completes the task successfully.

I am struggling to find out why the task fails without notice. Is there a way to attach to a task after it ran to see what it’s doing? Even when the API is deployed?

public static int runPreflighter(List<string> torun, int techID, string forcedEnv, preFlighterRunData runData, string sendEmail, string email)
{
    int runid = PTADB.startAsyncJob(techid, PTADB.getPreflighterId(forcedEnv), forcedEnv);
Task.Run(() =>
{
    try
    {
        foreach (string file in torun)
        {
            string preflightlog = Path.Combine(Path.GetDirectoryName(file), "Preflight_" + Path.GetFileNameWithoutExtension(file) + "_" + DateTime.Now.ToString("yyyyMMddHHmmss") + ".log");
            string preflightCmdLine = string.Format("-s {0} -p {1} "{2}" ", runData.inspireServer, runData.inspirePort, runData.wfdFile);
            preflightCmdLine += string.Format(" -warningconfig "vcs:\\Job Settings\WarningConfigs\9078.wpr" -e NULL -useincluded "*"  -l "{0}" ", preflightlog);
            PTADB.updateRunDetails(runid, "", "", "", "Preflighting for " + file, forcedEnv);

            try
            {
                ToolRunStatus status = new ToolRunStatus { toolrunid = runid, job = "", sub = "", cycle = "", status = "Preflighting for " + file };
                Ignite.runCommandLineAsBatch(runData.inspireServerFile, preflightCmdLine, file, "", "", "", "", "", forcedEnv, runData.hamburg, false, status);
            }
            catch (Exception ex)
            {
            }

            // mysteriously & randomly fails here, i.e. file 6 of 9
        }

        PTADB.endAsyncJob(runid, 'Y', "", forcedEnv);
    }
    catch (Exception ex)
    {
        // Update Database with error result, send email to user
        PTADB.endAsyncJob(runid, 'N', ex.Message, forcedEnv);

        // Send email to user that this failed
        List<string> to = new List<string> { email };
        string message = string.Format("Preflight failed for WFD {0} - {1}", runData.wfdFile, ex.Message);
        string subject = string.Format("Failed: Preflighter Encountered an error for {0}", runData.wfdFile);
        Email.sendEmail(subject, message, to);
      }
    });
    return runid;
}