Android Question Error during FTP.UploadFile

[doncx]

We have been uploading files successfully with FTP for a good while. Recently, we've been running into problems occasionally. I updated the code to display the exact error to users and we've seen this error several times: "500 Illegal Port Command" (see error image attached to this post).

Below are the two code snippets that connect and download. I think they're in order.

Here's my question: Is the error likely the result of a bad WiFi/Internet connection? Or could it be that the FTP functions are issuing a command that is not accepted by the server?

Since the process succeeds most of the time, I'm guessing it's a connection problem despite the fact that we've confirmed WiFi and connected to the server. Could it be something else?

I'd appreciate any knowledge you may have.

- Don

Connect:

    Socket1.Initialize("Socket1")
    Socket1.Connect( Main.config.Get( "FTPServer" ), Main.config.Get( "FTPPort" ), 5000 )
    btnUpload.visible = True
    btnCancel.visible = True

    If FTP.isInitialized = False Then
        FTP.Initialize( "FTP", Main.config.Get( "FTPServer" ), Main.config.Get( "FTPPort" ), Main.config.Get( "FTPUsername" ), Main.config.Get( "FTPPassword" ) )
        Log("initializing FTP")
    End If

Upload:

    Dim sf As Object = FTP.UploadFile( File.DirDefaultExternal, tfilename, False, tfilename )
    wait for (sf) FTP_UploadCompleted( serverpath As String, success As Boolean )
    If success = False Then
        Log(LastException.Message)
        MessageDialog.Show( "Error During Upload", LastException.Message, "Ok", "", "", 0, 0, .8 )
        MessageDialog.Show( "Upload Not Completed", "Please try again another time", "Ok", "", "", 0, 0, .8 )
        Activity.Finish
    Else
        File.Delete( File.DirDefaultExternal, tfilename )
        pbx.Progress = 100
        If file_number = file_list.Size Then
            MessageDialog.Show( "Upload Complete", "Data has been uploaded to CFRF", "Ok", "", "", 0, 0, .8 )
            Activity.Finish
            StartActivity(DownloadODDUpdate)
        Else
            DoThisUpload( file_list.Get(file_number) )
        End If
    End If

 

[DonManfred]

[B4X] Tip: Always set FTP.PassiveMode to True

I've just wasted an hour trying to understand why a desktop program that I'm using for many months failed to upload a file to a FTP server. I realized that the only thing that was recently changed is that B4J was running with Java 10. Mistakenly I assumed that it is related to IPv6 handling (the...

www.b4x.com

 

[doncx]

Thanks for passing that along. I'll give it a try.

 

[doncx]

I have tried setting passive mode to true but it did not make a difference.
So for now I'll have to assume that the illegal Port command message is the result of a poor connection.
Thanks for your suggestion.