Fixed: Fixed an issue where there could be a race condition during app update.

NzbDrone.Common/ProcessProvider.cs

@@ -57,6 +57,12 @@ namespace NzbDrone.Common
             return process;
         }
 
+        public virtual void WaitForExit(Process process)
+        {
+            Logger.Trace("Waiting for process {0} to exit.", process.ProcessName);
+            process.WaitForExit();
+        }
+
         public virtual void Kill(int processId)
         {
             if (processId == 0 || !Process.GetProcesses().Any(p => p.Id == processId))

NzbDrone.Core.Test/JobTests/AppUpdateJobFixture.cs

@@ -2,6 +2,7 @@
 using System;
 using System.Diagnostics;
 using System.IO;
+using FizzWare.NBuilder;
 using FluentAssertions;
 using Moq;
 using NUnit.Framework;

NzbDrone.Core/Jobs/AppUpdateJob.cs

@@ -82,12 +82,14 @@ namespace NzbDrone.Core.Jobs
             logger.Info("Starting update client");
             var startInfo = new ProcessStartInfo
                                 {
-                FileName = _enviromentProvider.GetUpdateClientExePath(),
-                Arguments = string.Format("{0} {1}", _enviromentProvider.NzbDroneProcessIdFromEnviroment, _configFileProvider.Guid)
-            };
+                                    FileName = _enviromentProvider.GetUpdateClientExePath(),
+                                    Arguments = string.Format("{0} {1}", _enviromentProvider.NzbDroneProcessIdFromEnviroment, _configFileProvider.Guid)
+                                };
 
-            _processProvider.Start(startInfo);
+            var process = _processProvider.Start(startInfo);
             notification.CurrentMessage = "Update in progress. NzbDrone will restart shortly.";
+
+           _processProvider.WaitForExit(process);
         }
     }
 }