constraint failed exceptions are translated to 409 conflict status codes.

src/NzbDrone.Api/ErrorManagement/NzbDroneErrorPipeline.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Data.SQLite;
 using FluentValidation;
 using NLog;
 using Nancy;
@@ -48,6 +49,21 @@ namespace NzbDrone.Api.ErrorManagement
                 }.AsResponse((HttpStatusCode)clientException.StatusCode);
             }
 
+
+            if (context.Request.Method == "PUT" || context.Request.Method == "POST")
+            {
+                var sqLiteException = exception as SQLiteException;
+
+                if (sqLiteException != null)
+                {
+                    if (sqLiteException.Message.Contains("constraint failed"))
+                        return new ErrorModel
+                        {
+                            Message = exception.Message,
+                        }.AsResponse(HttpStatusCode.Conflict);
+                }
+            }
+
             _logger.FatalException("Request Failed", exception);
 
             return new ErrorModel

src/NzbDrone.Api/NzbDrone.Api.csproj

@@ -68,6 +68,11 @@
     <Reference Include="System" />
     <Reference Include="System.Core" />
     <Reference Include="Microsoft.CSharp" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Data.SQLite, Version=1.0.84.0, Culture=neutral, PublicKeyToken=db937bc2d44ff139, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\Libraries\Sqlite\System.Data.SQLite.dll</HintPath>
+    </Reference>
   </ItemGroup>
   <ItemGroup>
     <Compile Include="..\NzbDrone.Common\Properties\SharedAssemblyInfo.cs">

src/UI/Instrumentation/ErrorHandler.js

@@ -79,6 +79,10 @@
                 message.message = xmlHttpRequest.responseJSON.message;
             }
 
+            if (xmlHttpRequest.status === 409) {
+                message.message = xmlHttpRequest.responseJSON.message;
+            }
+
             else {
                 message.message = '[{0}] {1} : {2}'.format(ajaxOptions.type, xmlHttpRequest.statusText, ajaxOptions.url);
             }