Don't try to process a download client item with an invalid path for the OS

src/NzbDrone.Common/Disk/OsPath.cs

@@ -153,6 +153,14 @@ namespace NzbDrone.Common.Disk
             }
         }
 
+        public bool IsValid
+        {
+            get
+            {
+                return _path.IsPathValid();
+            }
+        }
+
         private int GetFileNameIndex()
         {
             if (_path.Length < 2)

src/NzbDrone.Core.Test/Download/CompletedDownloadServiceFixture.cs

@@ -381,6 +381,30 @@ namespace NzbDrone.Core.Test.Download
             AssertCompletedDownload();
         }
 
+        [Test]
+        public void should_warn_if_path_is_not_valid_for_windows()
+        {
+            WindowsOnly();
+
+            _trackedDownload.DownloadItem.OutputPath = new OsPath(@"/invalid/Windows/Path");
+
+            Subject.Process(_trackedDownload);
+
+            AssertNoAttemptedImport();
+        }
+
+        [Test]
+        public void should_warn_if_path_is_not_valid_for_linux()
+        {
+            MonoOnly();
+
+            _trackedDownload.DownloadItem.OutputPath = new OsPath(@"C:\Invalid\Mono\Path");
+
+            Subject.Process(_trackedDownload);
+
+            AssertNoAttemptedImport();
+        }
+
         private void AssertNoAttemptedImport()
         {
             Mocker.GetMock<IDownloadedEpisodesImportService>()

src/NzbDrone.Core/Download/CompletedDownloadService.cs

@@ -3,6 +3,8 @@ using System.IO;
 using System.Linq;
 using NLog;
 using NzbDrone.Common.Disk;
+using NzbDrone.Common.EnsureThat;
+using NzbDrone.Common.EnvironmentInfo;
 using NzbDrone.Common.Extensions;
 using NzbDrone.Core.Configuration;
 using NzbDrone.Core.Download.TrackedDownloads;
@@ -72,6 +74,13 @@ namespace NzbDrone.Core.Download
                     return;
                 }
 
+                if ((OsInfo.IsWindows && !downloadItemOutputPath.IsWindowsPath) ||
+                    (OsInfo.IsNotWindows && !downloadItemOutputPath.IsUnixPath))
+                {
+                    trackedDownload.Warn("[{0}] is not a valid local path. You may need a Remote Path Mapping.", downloadItemOutputPath);
+                    return;
+                }
+
                 var downloadedEpisodesFolder = new OsPath(_configService.DownloadedEpisodesFolder);
 
                 if (downloadedEpisodesFolder.Contains(downloadItemOutputPath))