Retrieving error details from a process using BeginErrorReadLine() method inside a foreach loop

Hi

I have a wpf program for Video audio merging using the tool ffmpeg. I am using BackgroundWorker for accomplishing this task. On my DoWork method of my backgroundWorker I have a foreach loop. Inside that I am trying to write errors. I will include my code snippet

ObservableCollection<VideoAudioCombined> videosAudios = (ObservableCollection<VideoAudioCombined>)e.Argument;
            foreach (VideoAudioCombined va in videosAudios)
            {
                    
                    string absoluteVideoPath = aviVideoPath + va.Video;
                    string absoluteAudioPath = wavAudioPath + va.Audio;
                    string relativeVideoPathSplit = va.Video.Substring(0, va.Video.Length - 4);
                    string relativeAudioPathSplit = va.Audio.Substring(0, va.Audio.Length - 4);
                    string outputavi = relativeVideoPathSplit + "_" + relativeAudioPathSplit + ".avi";
                    string SelectedFileNameToSave = selectedFolder + outputavi;

                    interactiveProcess.StartInfo.Arguments = "-i " + absoluteVideoPath + "  -i  " + absoluteAudioPath +"   -c:v copy -c:a aac -strict experimental " + SelectedFileNameToSave + " ";
                    interactiveProcess.Start();
                    interactiveProcess.EnableRaisingEvents = true;
                    count++;
                    if (count == videosAudios.Count)
                    {
                        bw.ReportProgress(100);
                    }
                    else
                    {
                        bw.ReportProgress((count / videosAudios.Count) * 100);
                    }   
             interactiveProcess.ErrorDataReceived += new DataReceivedEventHandler((process, outputEventArgs) => processOutput += outputEventArgs.Data);
            interactiveProcess.BeginErrorReadLine();
            }
When I run it shows an exception " async read operation has already been started on the stream".,And with this exception application closes. Please help.