Saving settings failed if value was null.

src/NzbDrone.Api/Config/MediaManagementConfigResource.cs

@@ -44,7 +44,8 @@ namespace NzbDrone.Api.Config
 
                 SkipFreeSpaceCheckWhenImporting = model.SkipFreeSpaceCheckWhenImporting,
                 CopyUsingHardlinks = model.CopyUsingHardlinks,
-                EnableMediaInfo = model.EnableMediaInfo,
+                ExtraFileExtensions = model.ExtraFileExtensions,
+                EnableMediaInfo = model.EnableMediaInfo
             };
         }
     }

src/NzbDrone.Core.Test/Configuration/ConfigServiceFixture.cs

@@ -108,5 +108,19 @@ namespace NzbDrone.Core.Test.Configuration
 
             keys.Should().OnlyHaveUniqueItems();
         }
+
+        [Test]
+        public void should_ignore_null_properties()
+        {
+            Mocker.GetMock<IConfigRepository>()
+                  .Setup(v => v.Get("downloadedepisodesfolder"))
+                  .Returns(new Config { Id = 1, Key = "DownloadedEpisodesFolder", Value = @"C:\test".AsOsAgnostic() });
+
+            var dict = new Dictionary<string, object>();
+            dict.Add("DownloadedEpisodesFolder", null);
+            Subject.SaveConfigDictionary(dict);
+
+            Mocker.GetMock<IConfigRepository>().Verify(c => c.Upsert("downloadedepisodesfolder", It.IsAny<string>()), Times.Never());
+        }
     }
 }

src/NzbDrone.Core/Configuration/ConfigService.cs

@@ -55,7 +55,7 @@ namespace NzbDrone.Core.Configuration
             {
                 object currentValue;
                 allWithDefaults.TryGetValue(configValue.Key, out currentValue);
-                if (currentValue == null) continue;
+                if (currentValue == null || configValue.Value == null) continue;
 
                 var equal = configValue.Value.ToString().Equals(currentValue.ToString());