Fixed: Saving Newznab indexer when redirect was true

src/NzbDrone.Core/Indexers/IndexerBase.cs

@@ -208,12 +208,6 @@ namespace NzbDrone.Core.Indexers
 
             try
             {
-                // Ensure Redirect is true for Usenet protocols
-                if (Protocol == DownloadProtocol.Usenet || (SupportsRedirect && Redirect))
-                {
-                    failures.Add(new ValidationFailure("Redirect", "Redirect must be enabled for Usenet indexers"));
-                }
-
                 Test(failures).GetAwaiter().GetResult();
             }
             catch (Exception ex)

src/Prowlarr.Api.V1/Indexers/IndexerController.cs

@@ -1,4 +1,6 @@
+using System.Collections.Generic;
 using FluentValidation;
+using FluentValidation.Results;
 using NzbDrone.Core.Indexers;
 using NzbDrone.Core.Validation;
 using NzbDrone.SignalR;
@@ -24,5 +26,21 @@ namespace Prowlarr.Api.V1.Indexers
             SharedValidator.RuleFor(c => c.Priority).InclusiveBetween(1, 50);
             SharedValidator.RuleFor(c => c.DownloadClientId).SetValidator(downloadClientExistsValidator);
         }
+
+        protected override void Validate(IndexerDefinition definition, bool includeWarnings)
+        {
+            var instance = _providerFactory.GetInstance(definition);
+
+            // Ensure Redirect is true for Usenet protocols
+            if (instance is { Protocol: DownloadProtocol.Usenet, SupportsRedirect: true } && definition is { Redirect: false })
+            {
+                throw new ValidationException(new List<ValidationFailure>
+                {
+                    new("Redirect", "Redirect must be enabled for Usenet indexers")
+                });
+            }
+
+            base.Validate(definition, includeWarnings);
+        }
     }
 }

src/Prowlarr.Api.V1/ProviderControllerBase.cs

@@ -271,7 +271,7 @@ namespace Prowlarr.Api.V1
             BroadcastResourceChange(ModelAction.Deleted, message.ProviderId);
         }
 
-        private void Validate(TProviderDefinition definition, bool includeWarnings)
+        protected virtual void Validate(TProviderDefinition definition, bool includeWarnings)
         {
             var validationResult = definition.Settings.Validate();