Add Serilog logging together with an uncaught exception handler.

BulkPrinting/BulkPrinting/BatchForm.cs

 using System.Globalization;
 using System.Threading;
 using System.Windows.Forms;
+using Serilog;
 
 namespace BulkPrinting
 {
                 bool skipNewBatchCheck = false;
                 while (true)
                 {
+                    Log.Debug("Download thread sleeping");
+
                     bool forceNewBatchCheck;
                     lock (LoadingThreadLock)
                     {
                         RetryDownloads = false;
                         CheckForNewBatches = false;
                     }
+
+                    Log.Debug("Download thread woke up");
+
                     if (Globals.SessionMode == SessionModes.Online)
                     {
-                        Debug.WriteLine("Checking for downloads");
+                        Log.Debug("Checking for downloads");
 
                         if (forceNewBatchCheck)
                         {
                         {
                             while (!skipNewBatchCheck)
                             {
-                                Debug.WriteLine("Querying batches");
+                                Log.Debug("Querying batches");
+
                                 Page<Batch> BatchPage = new Page<Batch>();
                                 if (Utility.RESTRequest(ref BatchPage, String.Format("/api/batches/?lastBatchId={0}", lastSyncedBatchId)))
                                 {
                         }
                         catch (Exception e)
                         {
-                            Debug.WriteLine("Error while downloading batches");
-                            Debug.WriteLine(e.ToString());
+                            Log.Error(e, "Error while downloading batch list");
                         }
 
                         if (refreshGrid)
 
                                                     while (voucherCount < batch.DeliveredQuantity)
                                                     {
-                                                        Debug.WriteLine(String.Format("Downloading vouchers for batch {0} (got {1})", batchId, voucherCount));
+                                                        Log.Debug("Downloading vouchers for batch {0} ({1} so far)", batchId, voucherCount);
 
                                                         int page = voucherCount / voucherPageSize + 1;
                                                         int offset = voucherCount % voucherPageSize;
                                                             throw new Exception(String.Format("Too few vouchers were returned for batch {0}", batchId));
                                                         }
 
-                                                        Debug.WriteLine(String.Format("Downloaded vouchers for batch {0} (got {1})", batchId, voucherCount + voucherPage.Items.Count));
+                                                        Log.Debug("Downloaded vouchers for batch {0} ({1} so far)", batchId, voucherCount);
 
                                                         lock (Globals.DBWriteLock)
                                                         {
                                                             }
                                                         }
 
-                                                        Debug.WriteLine(String.Format("Inserted vouchers for batch {0}", batchId));
+                                                        Log.Debug("Inserted vouchers for batch {0}", batchId);
                                                     }
 
                                                     if (voucherCount > batch.DeliveredQuantity)
                                                     }
                                                     else
                                                     {
-                                                        Debug.WriteLine(String.Format("Batch {0} complete", batchId));
+                                                        Log.Debug("Batch {0} complete", batchId);
 
                                                         Utility.DBExecuteNonQuery(conn,
                                                             "UPDATE Batch SET Downloaded=1 WHERE Id=@BatchId",
                                             else if (batch == null)
                                             {
                                                 // Batch will only be null if we got a 404.
-                                                Debug.WriteLine(String.Format("Removing deleted batch {0}", batchId));
+                                                Log.Debug("Removing deleted batch {0}", batchId);
 
                                                 Utility.DBExecuteNonQuery(conn,
                                                     "DELETE FROM Voucher WHERE BatchId=@BatchId",
                                         }
                                         catch (Exception e)
                                         {
-                                            Debug.WriteLine(String.Format("Error while downloading vouchers for batch {0}", batchId));
-                                            Debug.WriteLine(e.ToString());
+                                            Log.Error(e, "Error while downloading vouchers for batch {0}", batchId);
                                         }
 
                                         if (refreshGrid)
                         }
                         catch (Exception e)
                         {
-                            Debug.WriteLine("Error while downloading vouchers");
-                            Debug.WriteLine(e.ToString());
+                            Log.Error(e, "Error while downloading vouchers");
                         }
                     }
+                    else
+                    {
+                        Log.Debug("Offline, skipping download check");
+                    }
                 }
             }
         }

BulkPrinting/BulkPrinting/BulkPrinting.csproj

     <Reference Include="Newtonsoft.Json, Version=10.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
       <HintPath>..\packages\Newtonsoft.Json.10.0.3\lib\net45\Newtonsoft.Json.dll</HintPath>
     </Reference>
+    <Reference Include="Serilog, Version=2.0.0.0, Culture=neutral, PublicKeyToken=24c2f752a8e58a10, processorArchitecture=MSIL">
+      <HintPath>..\packages\Serilog.2.6.0\lib\net46\Serilog.dll</HintPath>
+    </Reference>
+    <Reference Include="Serilog.Sinks.Debug, Version=1.0.0.0, Culture=neutral, PublicKeyToken=24c2f752a8e58a10, processorArchitecture=MSIL">
+      <HintPath>..\packages\Serilog.Sinks.Debug.1.0.0\lib\netstandard1.0\Serilog.Sinks.Debug.dll</HintPath>
+    </Reference>
+    <Reference Include="Serilog.Sinks.File, Version=2.0.0.0, Culture=neutral, PublicKeyToken=24c2f752a8e58a10, processorArchitecture=MSIL">
+      <HintPath>..\packages\Serilog.Sinks.File.4.0.0\lib\net45\Serilog.Sinks.File.dll</HintPath>
+    </Reference>
     <Reference Include="System" />
     <Reference Include="System.ComponentModel.DataAnnotations" />
     <Reference Include="System.Core" />

BulkPrinting/BulkPrinting/Program.cs

-using System;
+using Serilog;
+using System;
 using System.IO;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
 using System.Windows.Forms;
 
 namespace BulkPrinting
         [STAThread]
         static void Main()
         {
-            Globals.HDDSerialNumber = Utility.GetHDDSerial();
             Globals.MaxDBPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), Configuration.MaxDataPathName);
             Globals.MaxDBFilePath = Path.Combine(Globals.MaxDBPath, Configuration.MaxDBFileName);
+            Log.Logger = new LoggerConfiguration()
+                .MinimumLevel.Debug()
+                .WriteTo.Debug()
+                .WriteTo.File(
+                    Path.Combine(Globals.MaxDBPath, "application.log"),
+                    rollOnFileSizeLimit: true,
+                    fileSizeLimitBytes: 1024 * 1024,
+                    retainedFileCountLimit: 10,
+                    restrictedToMinimumLevel: Serilog.Events.LogEventLevel.Information)
+                .CreateLogger();
+
+            Log.Information("Starting");
+
+            AppDomain.CurrentDomain.UnhandledException += CurrentDomain_UnhandledException;
+
+            Globals.HDDSerialNumber = Utility.GetHDDSerial();
+
             Application.EnableVisualStyles();
             Application.SetCompatibleTextRenderingDefault(false);
             Application.Run(new UserLoginForm());
+
+            Log.Information("Exiting");
+        }
+
+        private static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
+        {
+            Log.Fatal((Exception)e.ExceptionObject, "Unhandled exception");
         }
     }
 }

BulkPrinting/BulkPrinting/packages.config

 <packages>
   <package id="EntityFramework" version="6.0.0" targetFramework="net461" />
   <package id="Newtonsoft.Json" version="10.0.3" targetFramework="net461" />
+  <package id="Serilog" version="2.6.0" targetFramework="net461" />
+  <package id="Serilog.Sinks.Debug" version="1.0.0" targetFramework="net461" />
+  <package id="Serilog.Sinks.File" version="4.0.0" targetFramework="net461" />
   <package id="System.Data.SQLite" version="1.0.106.0" targetFramework="net461" />
   <package id="System.Data.SQLite.Core" version="1.0.106.0" targetFramework="net461" />
   <package id="System.Data.SQLite.EF6" version="1.0.106.0" targetFramework="net461" />
   <package id="System.Data.SQLite.Linq" version="1.0.106.0" targetFramework="net461" />
+  <package id="System.Diagnostics.Debug" version="4.3.0" targetFramework="net461" />
   <package id="System.ValueTuple" version="4.3.1" targetFramework="net461" />
 </packages>