'This operation has already had OperationCompleted called on it and further calls are illegal.'

'This operation has already had OperationCompleted called on it and further calls are illegal.'

I am using vb.net and I am using a backgroundworker to download files when I call the ReportProgress the first time works but when I call it again further down the code of the Backgroundworker_dowork event it shows the error above ('This operation has already had OperationCompleted called on it and further calls are illegal.')

LINE 7 WORKS FINE BUT FOR SOME REASON LINE 14 GIVES ME THE ERROR CODE ABOVE

 Private Async Sub DownloaderWorkerAsyncOne_DoWork(sender As Object, e As DoWorkEventArgs) Handles DownloaderWorkerAsyncOne.DoWork

            Dim DownloadID As String = CStr(e.Argument)
            Dim CurrentDownloadPath As String = downloadsPath + DownloadID + "\"
            Dim CurrentDownloadFolder As StorageFolder
            Dim query As String = Await Pixels_Project_API.API.v1.GetVideo(CInt(DownloadID))
            DownloaderWorkerAsyncOne.ReportProgress(0, DownloadID + ":" + "Waiting")
            Try
                CurrentDownloadFolder = Await downloadsFolder.CreateFolderAsync(DownloadID, CreationCollisionOption.FailIfExists)
            Catch ex As Exception
                Alert("Error", "Folder exist")
                Exit Sub
            End Try
            DownloaderWorkerAsyncOne.ReportProgress(1, DownloadID + ":" + "Preparing") 'ERROR HERE 
//More code 
        End Sub

        Private Sub DownloaderWorkerAsyncOne_ProgressChanged(sender As Object, e As ProgressChangedEventArgs) Handles DownloaderWorkerAsyncOne.ProgressChanged
            Dim IDandState As String() = e.UserState.ToString.Split(":")
            ReportWork(CStr(IDandState(0)), CStr(IDandState(1) + ":" + CStr(e.ProgressPercentage) + "%"))
        End Sub

 Private Async Sub ReportWork(ob As String, status As String)
            Dim StatusProgress As String() = status.Split(":")
            For Each down As DownloadControl In ActiveDownloads.Children
                If down.MovieID = ob Then
                    down.Status = StatusProgress(0)
                    down.Progress = StatusProgress(1)
                    Exit For
                End If
            Next


        End Subhttps://www.experts-exchange.com/questions/29134964/'This-operation-has-already-had-OperationCompleted-called-on-it-and-further-calls-are-illegal-'.html#a42792335

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LVL 72

Éric MoreauSenior .Net ConsultantCommented: 2019-02-06

do you have code to share?

if your task is already completed, you shouldn't trigger the event.

Toni StenglerAuthor Commented: 2019-02-06

It seems that async operations and the BackgroundWorker component are not working well with each other. Have a look https://stackoverflow.com/questions/28230363/operation-already-completed-error-when-using-progress-bar

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Thank You so much! This is exactly what I was looking for.

'This operation has already had OperationCompleted called on it and further calls are illegal.'

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