diff --git a/ModernKeePass/Common/DatabaseHelper.cs b/ModernKeePass/Common/DatabaseHelper.cs
index a65b4d2..9afae3d 100644
--- a/ModernKeePass/Common/DatabaseHelper.cs
+++ b/ModernKeePass/Common/DatabaseHelper.cs
@@ -14,6 +14,9 @@ namespace ModernKeePass.Common
     {
         public enum DatabaseStatus
         {
+            Error = -3,
+            NoCompositeKey = -2,
+            CompositeKeyError = -1,
             Closed = 0,
             Opening = 1,
             Opened = 2
@@ -77,11 +80,11 @@ namespace ModernKeePass.Common
         /// <param name="key">The database composite key</param>
         /// <param name="createNew">True to create a new database before opening it</param>
         /// <returns>An error message, if any</returns>
-        public string Open(CompositeKey key, bool createNew = false)
+        public void Open(CompositeKey key, bool createNew = false)
         {
             try
             {
-                if (key == null) return "No composite key";
+                if (key == null) Status = DatabaseStatus.NoCompositeKey;
                 var ioConnection = IOConnectionInfo.FromFile(DatabaseFile);
                 if (createNew) _pwDatabase.New(ioConnection, key);
                 else _pwDatabase.Open(ioConnection, key, new NullStatusLogger());
@@ -92,19 +95,14 @@ namespace ModernKeePass.Common
                     RootGroup = new GroupVm(_pwDatabase.RootGroup, null, RecycleBinEnabled ? _pwDatabase.RecycleBinUuid : null);
                 }
             }
-            catch (ArgumentNullException)
-            {
-                return "Password cannot be empty";
-            }
             catch (InvalidCompositeKeyException)
             {
-                return "Wrong password";
+                Status = DatabaseStatus.CompositeKeyError;
             }
             catch (Exception ex)
             {
-                return ex.Message;
+                Status = DatabaseStatus.Error;
             }
-            return string.Empty;
         }
 
         /// <summary>
@@ -121,11 +119,19 @@ namespace ModernKeePass.Common
         /// <summary>
         /// Commit the changes to the currently opened database to file
         /// </summary>
-        public void Save()
+        public bool Save()
         {
-            // TODO: Save is disabled for now for Argon2Kdf because it corrupts DB (read works)
-            if (_pwDatabase == null || !_pwDatabase.IsOpen /*|| KdfPool.Get(KeyDerivation.KdfUuid) is Argon2Kdf*/) return;
-            _pwDatabase.Save(new NullStatusLogger());
+            if (_pwDatabase == null || !_pwDatabase.IsOpen) return false;
+            try
+            {
+                _pwDatabase.Save(new NullStatusLogger());
+                return true;
+            }
+            catch (Exception ex)
+            {
+                MessageDialogHelper.ShowErrorDialog(ex);
+            }
+            return false;
         }
 
         /// <summary>
diff --git a/ModernKeePass/Common/MessageDialogHelper.cs b/ModernKeePass/Common/MessageDialogHelper.cs
index 0ad69af..233bc9c 100644
--- a/ModernKeePass/Common/MessageDialogHelper.cs
+++ b/ModernKeePass/Common/MessageDialogHelper.cs
@@ -23,5 +23,17 @@ namespace ModernKeePass.Common
             // Show the message dialog
             await messageDialog.ShowAsync();
         }
+
+        public static async void ShowErrorDialog(Exception exception)
+        {
+            // Create the message dialog and set its content
+            var messageDialog = new MessageDialog(exception.Message, "Error occured");
+
+            // Add commands and set their callbacks; both buttons use the same callback function instead of inline event handlers
+            messageDialog.Commands.Add(new UICommand("OK"));
+            
+            // Show the message dialog
+            await messageDialog.ShowAsync();
+        }
     }
 }
diff --git a/ModernKeePass/Controls/CompositeKeyUserControl.xaml b/ModernKeePass/Controls/CompositeKeyUserControl.xaml
index 5fd5667..ebe555b 100644
--- a/ModernKeePass/Controls/CompositeKeyUserControl.xaml
+++ b/ModernKeePass/Controls/CompositeKeyUserControl.xaml
@@ -47,7 +47,7 @@
                      Foreground="{Binding PasswordComplexityIndicator, ConverterParameter=128, Converter={StaticResource DoubleToForegroungBrushConverter}}" 
                      Visibility="{Binding ShowComplexityIndicator, ElementName=UserControl, Converter={StaticResource BooleanToVisibilityConverter}}" />
         <CheckBox Grid.Row="1" Grid.Column="0" IsChecked="{Binding HasKeyFile, Mode=TwoWay}" />
-        <HyperlinkButton Grid.Row="1" Grid.Column="1" Margin="-15,0,0,0" Content="Select key file from disk..." IsEnabled="{Binding HasKeyFile}" Click="KeyFileButton_Click" />
+        <HyperlinkButton Grid.Row="1" Grid.Column="1" Margin="-15,0,0,0" Content="{Binding KeyFileText}" IsEnabled="{Binding HasKeyFile}" Click="KeyFileButton_Click" />
         <Button Grid.Column="0" Grid.Row="2" Content="OK" Click="OpenButton_OnClick" Background="{ThemeResource ListViewItemSelectedPointerOverBorderThemeBrush}" Foreground="{ThemeResource TextBoxBackgroundThemeBrush}" IsEnabled="{Binding IsValid}" />
         <TextBlock Grid.Column="1" Grid.Row="2" Height="28" FontSize="14" FontWeight="Light" HorizontalAlignment="Right" Text="{Binding Status}" Foreground="{Binding StatusType, Converter={StaticResource DiscreteIntToSolidColorBrushConverter}}" />
     </Grid>
diff --git a/ModernKeePass/Controls/CompositeKeyUserControl.xaml.cs b/ModernKeePass/Controls/CompositeKeyUserControl.xaml.cs
index 1a4d982..e590698 100644
--- a/ModernKeePass/Controls/CompositeKeyUserControl.xaml.cs
+++ b/ModernKeePass/Controls/CompositeKeyUserControl.xaml.cs
@@ -3,7 +3,6 @@ using Windows.Storage.Pickers;
 using Windows.System;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Input;
-using ModernKeePass.Common;
 using ModernKeePass.Events;
 using ModernKeePass.ViewModels;
 
@@ -56,7 +55,7 @@ namespace ModernKeePass.Controls
             ValidationChecking?.Invoke(this, new EventArgs());
 
             if (UpdateKey) Model.UpdateKey();
-            else if (Model.OpenDatabase(CreateNew) == DatabaseHelper.DatabaseStatus.Opened)
+            else if (Model.OpenDatabase(CreateNew))
             {
                 ValidationChecked?.Invoke(this, new PasswordEventArgs(Model.RootGroup));
             }
@@ -78,7 +77,9 @@ namespace ModernKeePass.Controls
             picker.FileTypeFilter.Add(".key");
 
             // Application now has read/write access to the picked file
-            Model.KeyFile = await picker.PickSingleFileAsync();
+            var file = await picker.PickSingleFileAsync();
+            if (file == null) return;
+            Model.KeyFile = file;
         }
     }
 }
diff --git a/ModernKeePass/ViewModels/CompositeKeyVm.cs b/ModernKeePass/ViewModels/CompositeKeyVm.cs
index 46944a0..8927b24 100644
--- a/ModernKeePass/ViewModels/CompositeKeyVm.cs
+++ b/ModernKeePass/ViewModels/CompositeKeyVm.cs
@@ -1,4 +1,5 @@
-using Windows.Storage;
+using System.Text;
+using Windows.Storage;
 using Windows.UI.Xaml;
 using ModernKeePass.Common;
 using ModernKeePassLib.Cryptography;
@@ -24,6 +25,7 @@ namespace ModernKeePass.ViewModels
         private string _status;
         private StatusTypes _statusType;
         private StorageFile _keyFile;
+        private string _keyFileText = "Select key file from disk...";
 
         public bool HasPassword
         {
@@ -45,7 +47,7 @@ namespace ModernKeePass.ViewModels
             }
         }
 
-        public bool IsValid => HasPassword || HasKeyFile;
+        public bool IsValid => HasPassword || HasKeyFile && KeyFile != null;
 
         public string Status
         {
@@ -76,18 +78,37 @@ namespace ModernKeePass.ViewModels
             set
             {
                 _keyFile = value;
-                UpdateStatus($"Key file: {value.Name}", StatusTypes.Normal);
+                KeyFileText = value?.Name;
+                OnPropertyChanged("IsValid");
             }
         }
 
+        public string KeyFileText
+        {
+            get { return _keyFileText; }
+            set { SetProperty(ref _keyFileText, value); }
+        }
+
         public GroupVm RootGroup { get; set; }
         public double PasswordComplexityIndicator => QualityEstimation.EstimatePasswordBits(Password?.ToCharArray());
         
-        public DatabaseHelper.DatabaseStatus OpenDatabase(bool createNew)
+        public bool OpenDatabase(bool createNew)
         {
-            UpdateStatus(_app.Database.Open(CreateCompositeKey(), createNew), StatusTypes.Error);
-            RootGroup = _app.Database.RootGroup;
-            return _app.Database.Status;
+            _app.Database.Open(CreateCompositeKey(), createNew);
+            switch (_app.Database.Status)
+            {
+                case DatabaseHelper.DatabaseStatus.Opened:
+                    RootGroup = _app.Database.RootGroup;
+                    return true;
+                case DatabaseHelper.DatabaseStatus.CompositeKeyError:
+                    var errorMessage = new StringBuilder("Error: wrong ");
+                    if (HasPassword) errorMessage.Append("password");
+                    if (HasPassword && HasKeyFile) errorMessage.Append(" or ");
+                    if (HasKeyFile) errorMessage.Append("key file");
+                    UpdateStatus(errorMessage.ToString(), StatusTypes.Error);
+                    break;
+            }
+            return false;
         }
 
         public void UpdateKey()
diff --git a/ModernKeePass/ViewModels/SaveVm.cs b/ModernKeePass/ViewModels/SaveVm.cs
index e10863e..26b6502 100644
--- a/ModernKeePass/ViewModels/SaveVm.cs
+++ b/ModernKeePass/ViewModels/SaveVm.cs
@@ -8,9 +8,7 @@ namespace ModernKeePass.ViewModels
         public void Save(bool close = true)
         {
             var app = (App)Application.Current;
-            app.Database.Save();
-            if (!close) return;
-            app.Database.Close();
+            if (close && app.Database.Save()) app.Database.Close();
         }
 
         internal void Save(StorageFile file)