Compact Framework 3.5 App Loses Font Styles

Question

I have a basic Compact Framework v3.5 application running on Zebra MC2180 mobile barcode scanners and have a very intermittent issue.

Occasionally (after approx 1 in 20 or so scans), all font styles set on all labels, buttons, etc are lost and revert to the default size 9 font. Any specific "bold" settings or font sizes are lost.

No exceptions are thrown, there is no indication anything has gone wrong except the missing font styles....

If I write a trace on the font style property, when the font info is lost, I get a System.Drawing exception but no further information. It seems to me it is trying to access an unset property? Eg:

System.Diagnostics.Trace.WriteLine(btn_orderChecking.Font.Style);

Produces (very intermittently):

A first chance exception of type 'System.Exception' occurred in System.Drawing.dll
A first chance exception of type 'System.Reflection.TargetInvocationException' occurred in mscorlib.dll
A first chance exception of type 'System.Exception' occurred in System.Windows.Forms.dll
A first chance exception of type 'System.Threading.ThreadAbortException' occurred in Symbol.Barcode2.dll
A first chance exception of type 'System.Threading.ThreadAbortException' occurred in mscorlib.dll
A first chance exception of type 'System.Threading.ThreadAbortException' occurred in System.Windows.Forms.dll
A first chance exception of type 'System.ObjectDisposedException' occurred in mscorlib.dll
The program '[0x2C50F9A] MC2180.exe: Managed' has exited with code 0 (0x0).

The method producing the error is below. This code snippet takes a barcode and displays product info (pulled from a web service)

case PANEL_PLU:

                        clearPLUpanel();
                        pluDataPartno.Text = "LOADING"; // This never gets seen - panel doesn't get repainted
                        lblScanBarcode.Hide();
                        panelError.Hide();

                        payload = new Dictionary<String, String>();
                        payload.Add("barcode", scanData.Text);
                        request = new dataRequest("plu",payload);
                        res = dataTransfer.sendRequest(request);

                        if (res.result == "ok")
                        {
                            // We're good, populate and show fields
                            playHappyBeep();
                            pluItem_Id = res.item_id;
                            pluDataPartno.Text = res.item_partno;
                            pluDataName.Text = res.item_name;
                            pluDataFreeStock.Text = res.item_freeStock.ToString();
                            pluDatalAllocated.Text = res.allocated_stock.ToString();
                            pluDataLoc.Text = res.loc_name;
                            pluDataShelfStock.Text = res.item_shelfStock.ToString();
                            pluLabelAllocated.Show();
                            pluLabelFreeStock.Show();
                            pluLabelLoc.Show();
                            pluLabelShelfStock.Show();
                            pluImage.Show();
                            plu_btnChangeLoc.Show();
                            plu_btnAutoLocate.Show();

                            if (res.image_url.StartsWith("http")) {
                                 pluImage.Url = new System.Uri(res.image_url);
                            }

                            if (res.item_freeStock > 0)
                            {
                                pluDataFreeStock.ForeColor = Color.Green;
                            }
                            else
                            {
                                pluDataFreeStock.ForeColor = Color.Red;
                            }

                        }
                        else
                        {
                            playErrorBeep();
                            clearPLUpanel();
                            lblErrorHeadline.Text = res.error_info;
                            panelError.Show();                               
                        }

                        System.Diagnostics.Trace.WriteLine(btn_orderChecking.Font.Style); // This is the line that occasionally throws the exception

                        break;

Answer 1

This error does not occur in OS version 82.34.004. You should to update OS to this version. Ondřej