diff --git a/src/Koogle.Infrastructure/Repositories/BookingCategoryRepository.cs b/src/Koogle.Infrastructure/Repositories/BookingCategoryRepository.cs
index 7a2c784..b70bcfd 100644
--- a/src/Koogle.Infrastructure/Repositories/BookingCategoryRepository.cs
+++ b/src/Koogle.Infrastructure/Repositories/BookingCategoryRepository.cs
@@ -51,7 +51,15 @@ public class BookingCategoryRepository(IDbContextFactory<AppDbContext> contextFa
         entity.Id = Guid.NewGuid();
         entity.CreatedAt = DateTime.UtcNow;
         await context.BookingCategories.AddAsync(entity, ct);
-        await context.SaveChangesAsync(ct);
+        try
+        {
+            await context.SaveChangesAsync(ct);
+        }
+        catch (Exception e)
+        {
+
+            throw;
+        }
         return entity;
     }
 
diff --git a/src/Koogle.Web/Components/Pages/Admin/ManageRolesDialog.razor b/src/Koogle.Web/Components/Pages/Admin/ManageRolesDialog.razor
index 2ef8319..6be3c20 100644
--- a/src/Koogle.Web/Components/Pages/Admin/ManageRolesDialog.razor
+++ b/src/Koogle.Web/Components/Pages/Admin/ManageRolesDialog.razor
@@ -50,7 +50,7 @@
 
     [Parameter] public UserDto User { get; set; } = null!;
 
-    private readonly string[] _availableRoles = { UserRole.Viewer, UserRole.Editor, UserRole.Admin };
+    private readonly string[] _availableRoles = { UserRole.Viewer, UserRole.Editor, UserRole.Treasurer, UserRole.Admin };
     private bool _isProcessing;
     private bool _hasChanges;
 
diff --git a/src/Koogle.Web/Components/Pages/CashBook/CategoryDialog.razor b/src/Koogle.Web/Components/Pages/CashBook/CategoryDialog.razor
index b204e9a..9dcb7cd 100644
--- a/src/Koogle.Web/Components/Pages/CashBook/CategoryDialog.razor
+++ b/src/Koogle.Web/Components/Pages/CashBook/CategoryDialog.razor
@@ -15,6 +15,7 @@
                 Required="true"
                 RequiredError="Name ist erforderlich"
                 Immediate="true"
+                Disabled="_isSystemCategory"
                 Class="mb-4" />
 
             <MudTextField @bind-Value="_description"
@@ -106,6 +107,7 @@
 
     private MudForm? _form;
     private bool _isValid;
+    private bool _isSystemCategory;
     private string _name = "";
     private string? _description;
     private BookingCategoryType _categoryType = BookingCategoryType.Income;
@@ -145,6 +147,7 @@
             _color = string.IsNullOrWhiteSpace(Category.Color) ? null : new MudColor(Category.Color);
             _icon = Category.Icon;
             _isActive = Category.IsActive;
+            _isSystemCategory = Category.IsSystemCategory;
         }
     }
 
diff --git a/src/Koogle.Web/Components/Pages/CashBook/MembershipFeeDialog.razor b/src/Koogle.Web/Components/Pages/CashBook/MembershipFeeDialog.razor
index 1813713..547cc90 100644
--- a/src/Koogle.Web/Components/Pages/CashBook/MembershipFeeDialog.razor
+++ b/src/Koogle.Web/Components/Pages/CashBook/MembershipFeeDialog.razor
@@ -11,9 +11,8 @@
 
         <MudStack Row="true" Spacing="4" Class="mb-4">
             <MudSelect T="int" @bind-Value="_selectedMonth" Label="Monat" Style="width: 150px;">
-                @for (int m = 1; m <= 12; m++)
+                @foreach (var month in Enumerable.Range(1, 12))
                 {
-                    var month = m;
                     <MudSelectItem Value="@month">@GetMonthName(month)</MudSelectItem>
                 }
             </MudSelect>