diff --git a/Elwig/Windows/ChartWindow.xaml.cs b/Elwig/Windows/ChartWindow.xaml.cs
index f978412..cdbe960 100644
--- a/Elwig/Windows/ChartWindow.xaml.cs
+++ b/Elwig/Windows/ChartWindow.xaml.cs
@@ -74,8 +74,9 @@ namespace Elwig.Windows {
             InitializeComponent();
             Year = year;
             AvNr = avnr;
-            Season = Context.Seasons.Find(year) ?? throw new ArgumentException("Season not found");
-            PaymentVar = Context.PaymentVariants.Find(year, avnr) ?? throw new ArgumentException("PaymentVar not found");
+            using var ctx = new AppDbContext();
+            Season = ctx.Seasons.Find(year) ?? throw new ArgumentException("Season not found");
+            PaymentVar = ctx.PaymentVariants.Find(year, avnr) ?? throw new ArgumentException("PaymentVar not found");
             Title = $"{PaymentVar?.Name} - Lese {year} - Elwig";
             LockContext = true;
         }
@@ -100,15 +101,16 @@ namespace Elwig.Windows {
         }
 
         private async Task RefreshGraphList() {
-            PaymentVar = await Context.PaymentVariants.FindAsync(Year, AvNr) ?? throw new ArgumentException("PaymentVar not found");
-            Season = await Context.Seasons.FindAsync(Year) ?? throw new ArgumentException("Season not found");
+            using var ctx = new AppDbContext();
+            PaymentVar = await ctx.PaymentVariants.FindAsync(Year, AvNr) ?? throw new ArgumentException("PaymentVar not found");
+            Season = await ctx.Seasons.FindAsync(Year) ?? throw new ArgumentException("Season not found");
 
             try {
-                var data = EditBillingData.FromJson(PaymentVar.Data, Utils.GetVaributes(Context, Year));
-                var paymentEntries = data.GetPaymentGraphEntries(Context, Season);
+                var data = EditBillingData.FromJson(PaymentVar.Data, Utils.GetVaributes(ctx, Year));
+                var paymentEntries = data.GetPaymentGraphEntries(ctx, Season);
                 GraphEntries = [
                     ..paymentEntries,
-                    ..data.GetQualityGraphEntries(Context, Season, paymentEntries.Any() ? paymentEntries.Max(e => e.Id) : 0)
+                    ..data.GetQualityGraphEntries(ctx, Season, paymentEntries.Any() ? paymentEntries.Max(e => e.Id) : 0)
                 ];
             } catch (KeyNotFoundException ex) {
                 var key = ex.Message.Split('\'')[1].Split('\'')[0];
@@ -123,7 +125,7 @@ namespace Elwig.Windows {
                 MessageBox.Show("Fehler beim Laden der Auszahlungsvariante:\n\n" + ex.Message, "Fehler",
                     MessageBoxButton.OK, MessageBoxImage.Error);
             }
-            Vaributes = Utils.GetVaributeList(Context, Year);
+            Vaributes = Utils.GetVaributeList(ctx, Year);
             GraphEntries.ForEach(e => {
                 e.Vaributes.ForEach(v => {
                     var found = Vaributes.Find(a => a.Variety?.SortId == v.Variety?.SortId && a.Attribute?.AttrId == v.Attribute?.AttrId && a.Cultivation?.CultId == v.Cultivation?.CultId);
@@ -505,9 +507,9 @@ namespace Elwig.Windows {
                 PrimaryMarkedPoint = Highlighted.Index;
                 if (ActiveGraph != Highlighted.Graph) ChangeActiveGraph(Highlighted.Graph);
 
-                ChangeMarker(PrimaryMarkedPointPlot, true, ActiveGraph.GetOechsleAt(PrimaryMarkedPoint), ActiveGraph.GetPriceAt(PrimaryMarkedPoint));
+                ChangeMarker(PrimaryMarkedPointPlot, true, ActiveGraph!.GetOechsleAt(PrimaryMarkedPoint), ActiveGraph.GetPriceAt(PrimaryMarkedPoint));
 
-                OechsleInput.Text = Highlighted.Graph.GetOechsleAt(Highlighted.Index).ToString();
+                OechsleInput.Text = Highlighted.Graph!.GetOechsleAt(Highlighted.Index).ToString();
                 PriceInput.Text = Highlighted.Graph.GetPriceAt(Highlighted.Index).ToString();
 
                 EnableActionButtons();
@@ -643,20 +645,18 @@ namespace Elwig.Windows {
         }
 
         private async void SaveButton_Click(object sender, RoutedEventArgs e) {
-            var origData = BillingData.FromJson(PaymentVar.Data);
-            var data = BillingData.FromGraphEntries(GraphEntries, origData, Utils.GetVaributes(Context, Year),
-                AllVaributesAssigned, AllVaributesAssignedAbgew);
-
-            EntityEntry<PaymentVar>? tr = null;
             try {
+                using var ctx = new AppDbContext();
+                var origData = BillingData.FromJson(PaymentVar.Data);
+                var data = BillingData.FromGraphEntries(GraphEntries, origData, Utils.GetVaributes(ctx, Year),
+                    AllVaributesAssigned, AllVaributesAssignedAbgew);
+
                 PaymentVar.Data = data.ToJsonString();
-                tr = Context.Update(PaymentVar);
-                await Context.SaveChangesAsync();
+                ctx.Update(PaymentVar);
+                await ctx.SaveChangesAsync();
                 LockContext = false;
-                tr = null;
                 await App.HintContextChange();
             } catch (Exception exc) {
-                if (tr != null) await tr.ReloadAsync();
                 var str = "Der Eintrag konnte nicht in der Datenbank gespeichert werden!\n\n" + exc.Message;
                 if (exc.InnerException != null) str += "\n\n" + exc.InnerException.Message;
                 MessageBox.Show(str, "Auszahlungsvariante speichern", MessageBoxButton.OK, MessageBoxImage.Error);