diff --git a/src/OrchardCore.Modules/OrchardCore.Alias/Indexes/AliasPartIndex.cs b/src/OrchardCore.Modules/OrchardCore.Alias/Indexes/AliasPartIndex.cs
index d93a5d1553c..632d326e7b2 100644
--- a/src/OrchardCore.Modules/OrchardCore.Alias/Indexes/AliasPartIndex.cs
+++ b/src/OrchardCore.Modules/OrchardCore.Alias/Indexes/AliasPartIndex.cs
@@ -44,7 +44,7 @@ public override async Task UpdatedAsync(UpdateContentContext context)
 
                 // Search for this part.
                 var contentTypeDefinition = await _contentDefinitionManager.GetTypeDefinitionAsync(context.ContentItem.ContentType);
-                if (!contentTypeDefinition.Parts.Any(ctd => ctd.Name == nameof(AliasPart)))
+                if (contentTypeDefinition?.Parts is not null && !contentTypeDefinition.Parts.Any(ctd => string.Equals(ctd.Name, nameof(AliasPart), StringComparison.Ordinal)))
                 {
                     context.ContentItem.Remove<AliasPart>();
                     _partRemoved.Add(context.ContentItem.ContentItemId);