[Android] Fix DatePicker MinimumDate/MaximumDate not updating dynamically

src/Controls/tests/TestCases.HostApp/Issues/Issue19256.cs

@@ -0,0 +1,79 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 19256, "DatePicker control minimum date issue", PlatformAffected.Android)]
+public class Issue19256 : ContentPage
+{
+	readonly DatePicker _leftDatePicker;
+	readonly DatePicker _rightDatePicker;
+
+	static readonly DateTime BaseDate = new DateTime(2025, 6, 15);
+	static readonly DateTime FutureDate = new DateTime(2025, 6, 25);  // BaseDate + 10 days
+	static readonly DateTime EarlierDate = new DateTime(2025, 6, 20); // BaseDate + 5 days
+
+	public Issue19256()
+	{
+		_leftDatePicker = new DatePicker
+		{
+			HorizontalOptions = LayoutOptions.Center,
+			AutomationId = "LeftDatePicker",
+			Date = BaseDate
+		};
+		_leftDatePicker.DateSelected += OnLeftDateSelected;
+
+		_rightDatePicker = new DatePicker
+		{
+			HorizontalOptions = LayoutOptions.Center,
+			AutomationId = "RightDatePicker",
+			Date = BaseDate,
+			MinimumDate = BaseDate
+		};
+
+		var setFutureDateButton = new Button
+		{
+			AutomationId = "SetFutureDateButton",
+			Text = "Set Future Date"
+		};
+		setFutureDateButton.Clicked += OnSetFutureDateClicked;
+
+		var setEarlierDateButton = new Button
+		{
+			AutomationId = "SetEarlierDateButton",
+			Text = "Set Earlier Date"
+		};
+		setEarlierDateButton.Clicked += OnSetEarlierDateClicked;
+
+		Content = new VerticalStackLayout
+		{
+			Spacing = 20,
+			Padding = 20,
+			Children =
+				{
+					_leftDatePicker,
+					_rightDatePicker,
+					setFutureDateButton,
+					setEarlierDateButton
+				}
+		};
+	}
+
+
+	void OnLeftDateSelected(object sender, DateChangedEventArgs e)
+	{
+		_rightDatePicker.MinimumDate = e.NewDate;
+
+		if (_rightDatePicker.Date < e.NewDate)
+		{
+			_rightDatePicker.Date = e.NewDate;
+		}
+	}
+
+	void OnSetFutureDateClicked(object sender, EventArgs e)
+	{
+		_leftDatePicker.Date = FutureDate;
+	}
+
+	void OnSetEarlierDateClicked(object sender, EventArgs e)
+	{
+		_leftDatePicker.Date = EarlierDate;
+	}
+}

src/Controls/tests/TestCases.HostApp/Issues/Issue33583.cs

@@ -0,0 +1,39 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 33583, "DatePicker does not update MinimumDate / MaximumDate in the Popup after first opening", PlatformAffected.Android)]
+public class Issue33583 : TestContentPage
+{
+    DatePicker _datePicker;
+
+    protected override void Init()
+    {
+        _datePicker = new DatePicker
+        {
+            AutomationId = "TestDatePicker",
+            HorizontalOptions = LayoutOptions.Center,
+            MinimumDate = new DateTime(2025, 1, 4),
+            MaximumDate = new DateTime(2025, 1, 28),
+            Date = new DateTime(2025, 1, 15)
+        };
+
+        var changeMaxDateButton = new Button
+        {
+            Text = "Change MaximumDate to 2027",
+            AutomationId = "ChangeMaxDateButton"
+        };
+        changeMaxDateButton.Clicked += (s, e) =>
+        {
+            _datePicker.MaximumDate = new DateTime(2027, 12, 31);
+        };
+
+        Content = new VerticalStackLayout
+        {
+            Spacing = 10,
+            Children =
+            {
+                _datePicker,
+                changeMaxDateButton
+            }
+        };
+    }
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue19256.cs

@@ -0,0 +1,53 @@
+// Android specific scenario
+#if ANDROID
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue19256 : _IssuesUITest
+{
+	public Issue19256(TestDevice device) : base(device)
+	{
+	}
+
+	public override string Issue => "DatePicker control minimum date issue";
+
+	[Test]
+	[Category(UITestCategories.DatePicker)]
+	public void DatePickerMinimumDateShouldUpdateDynamically()
+	{
+		Exception? exception = null;
+
+		App.WaitForElement("LeftDatePicker");
+		App.WaitForElement("RightDatePicker");
+
+		// Step 1: Set LEFT to future date (June 25) - RIGHT MinimumDate becomes June 25
+		App.Tap("SetFutureDateButton");
+
+		// Step 2: Open RIGHT DatePicker to see MinimumDate is June 25
+		App.Tap("RightDatePicker");
+
+		// Screenshot 1: Shows dates before June 25 are disabled
+		VerifyScreenshotOrSetException(ref exception, "DatePickerMinimumDateShouldUpdateDynamically_FutureDate");
+
+		// Dismiss the dialog
+		App.Tap("Cancel");
+
+		// Step 3: Set LEFT to earlier date (June 20) - RIGHT MinimumDate should become June 20
+		App.Tap("SetEarlierDateButton");
+
+		// Step 4: Open RIGHT DatePicker again to verify MinimumDate updated
+		App.Tap("RightDatePicker");
+
+		// Screenshot 2: Should show dates from June 20 are now enabled (not June 25)
+		VerifyScreenshotOrSetException(ref exception, "DatePickerMinimumDateShouldUpdateDynamically_EarlierDate");
+
+		if (exception is not null)
+		{
+			throw exception;
+		}
+	}
+}
+#endif

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue33583.cs

@@ -0,0 +1,50 @@
+#if !IOS // iOS DatePicker uses a wheel picker, not a calendar dialog - cannot verify disabled dates visually
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue33583 : _IssuesUITest
+{
+#if ANDROID
+	const string DismissDatePicker = "Cancel";
+#elif WINDOWS
+	const string DismissDatePicker = "16"; // Tap a date to close
+#elif MACCATALYST
+    const string DismissDatePicker = "ChangeMaxDateButton"; // Tap another element to dismiss/unfocus
+#endif
+
+    public Issue33583(TestDevice testDevice) : base(testDevice)
+    {
+    }
+
+    public override string Issue => "DatePicker does not update MinimumDate / MaximumDate in the Popup after first opening";
+
+    [Test]
+    [Category(UITestCategories.DatePicker)]
+    public void VerifyMaximumDateInRuntime()
+    {
+        // Wait for the page to load
+        App.WaitForElement("TestDatePicker");
+
+        // Step 1: Open the date picker the first time by tapping it directly
+        App.Tap("TestDatePicker");
+
+        // Dismiss the dialog
+        App.Tap(DismissDatePicker);
+
+        // Step 2: Change the MaximumDate to 2027
+        App.WaitForElement("ChangeMaxDateButton");
+        App.Tap("ChangeMaxDateButton");
+
+        // Step 3: Open the date picker again - this is where the bug would occur
+        // Before the fix, the dialog would still show the old MaximumDate constraints
+        App.Tap("TestDatePicker");
+
+        // Verify the DatePicker dialog shows updated constraints via screenshot
+        // With the fix, dates beyond Jan 28 should now be selectable
+        VerifyScreenshot();
+    }
+}
+#endif

src/Core/src/Handlers/DatePicker/DatePickerHandler.Android.cs

@@ -55,12 +55,7 @@ void OnViewAttachedToWindow(object? sender = null, View.ViewAttachedToWindowEven
 
 		protected override void DisconnectHandler(MauiDatePicker platformView)
 		{
-			if (_dialog != null)
-			{
-				_dialog.DismissEvent -= OnDialogDismiss;
-				_dialog.Dismiss();
-				_dialog = null;
-			}
+			ResetDialog();
 
 			platformView.ViewAttachedToWindow -= OnViewAttachedToWindow;
 			platformView.ViewDetachedFromWindow -= OnViewDetachedFromWindow;
@@ -106,13 +101,47 @@ public static partial void MapDate(IDatePickerHandler handler, IDatePicker dateP
 		public static partial void MapMinimumDate(IDatePickerHandler handler, IDatePicker datePicker)
 		{
 			if (handler is DatePickerHandler platformHandler)
-				handler.PlatformView?.UpdateMinimumDate(datePicker, platformHandler._dialog);
+			{
+				// Force dialog recreation when MinimumDate is provided.
+				// Android's DatePickerDialog caches min/max dates internally,
+				// making it unreliable to update them after the dialog is created.
+				if (datePicker.MinimumDate is not null)
+				{
+					platformHandler.ResetDialog();
+				}
+				else
+				{
+					handler.PlatformView?.UpdateMinimumDate(datePicker, platformHandler._dialog);
+				}
+			}
 		}
 
 		public static partial void MapMaximumDate(IDatePickerHandler handler, IDatePicker datePicker)
 		{
 			if (handler is DatePickerHandler platformHandler)
-				handler.PlatformView?.UpdateMaximumDate(datePicker, platformHandler._dialog);
+			{
+				// Force dialog recreation when MaximumDate is provided.
+				// Android's DatePickerDialog caches min/max dates internally,
+				// making it unreliable to update them after the dialog is created.
+				if (datePicker.MaximumDate is not null)
+				{
+					platformHandler.ResetDialog();
+				}
+				else
+				{
+					handler.PlatformView?.UpdateMaximumDate(datePicker, platformHandler._dialog);
+				}
+			}
+		}
+
+		void ResetDialog()
+		{
+			if (_dialog is not null)
+			{
+				_dialog.DismissEvent -= OnDialogDismiss;
+				_dialog.Dismiss();
+				_dialog = null;
+			}
 		}
 
 		public static partial void MapCharacterSpacing(IDatePickerHandler handler, IDatePicker datePicker)
@@ -170,6 +199,13 @@ void ShowPickerDialog(DateTime? date)
 			if (_dialog is null)
 			{
 				_dialog = CreateDatePickerDialog(year, month, day);
+
+				// Apply min/max constraints to newly created dialog
+				if (VirtualView is not null)
+				{
+					PlatformView?.UpdateMinimumDate(VirtualView, _dialog);
+					PlatformView?.UpdateMaximumDate(VirtualView, _dialog);
+				}
 			}
 			else
 			{