System.NullReferenceException at NavigationRenderer.SetStatusBarStyle() #29535

MateusMiotto · 2025-05-15T20:46:01Z

Description

After migrating from .net8 to .net9 this issue appeared.
After navigating from a login screen to the app's home page, which does not have a status bar, I receive a System.NullReferenceException

[0:] * Unhandled Exception *: System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.Maui.Controls.Handlers.Compatibility.NavigationRenderer.SetStatusBarStyle()
   at Microsoft.Maui.Controls.Handlers.Compatibility.NavigationRenderer.ViewWillAppear(Boolean animated)
   at Microsoft.Maui.Controls.Handlers.Compatibility.NavigationRenderer.__Registrar_Callbacks__.callback_1068_Microsoft_Maui_Controls_Handlers_Compatibility_NavigationRenderer_ViewWillAppear(IntPtr pobj, IntPtr sel, Byte p0, IntPtr* exception_gchandle)
--- End of stack trace from previous location ---
   at ObjCRuntime.Runtime.ThrowException(IntPtr gchandle) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/ObjCRuntime/Runtime.cs:line 2742
   at UIKit.UIApplication.UIApplicationMain(Int32 argc, String[] argv, IntPtr principalClassName, IntPtr delegateClassName) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/UIKit/UIApplication.cs:line 64
   at UIKit.UIApplication.Main(String[] args, Type principalClass, Type delegateClass) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/UIKit/UIApplication.cs:line 96
   at App.Program.Main(String[] args) in C:\dev\App\Platforms\iOS\Program.cs:line 16

I am using NavigationPage.HasNavigationBar as false at HomePage but using it as true did not throw an exception in my tests
The Home page is a FlyoutPage and the details is the page with the tag NavigationPage.HasNavigationBar
This crash happens only when i try to navigate from login page to home page, if the application starts directly in that, the exception doesn't happens, using NavigationPage.HasNavigationBar as true or false.

Steps to Reproduce

I don't know exactly the reason of that, so, don't have a sample

Link to public reproduction project repository

No response

Version with bug

9.0.70 SR7

Is this a regression from previous behavior?

Yes, this used to work in .NET MAUI

Last version that worked well

8.0.80 SR8

Affected platforms

iOS

Affected platform versions

iOS only

Did you find any workaround?

Nop

Relevant log output

The text was updated successfully, but these errors were encountered:

similar-issues-ai · 2025-05-15T20:46:14Z

We've found some similar issues:

If any of the above are duplicates, please consider closing this issue out and adding additional context in the original issue.

Note: You can give me feedback by 👍 or 👎 this comment.

PureWeen · 2025-05-15T21:09:04Z

Can you extract out something into a repro? That direct code hasn't changed in a number of years so it's hard to say.

NET9 does cleanup code a bit more aggressively than NET8 did so I'm guessing that's related

MateusMiotto · 2025-05-16T12:26:56Z

For me, the exception does not happen in all reproductions, it is something almost random.

I am not using shell for navigation.

I can describe that I have a Login screen for the tenant, I create a navigation stack for another user login screen.

When the login is successful I need to replace the app's mainPage with a Flyout Page that contains the menu items and the Details screen.

I know this is not the best way to do it, but using Navigation I did not get the desired behavior.

Only in this specific situation I replace:

Application.Current.Windows[0].Page = page;

When the app is closed and opened again, if the user is already logged in, I directly assign the MainPage as my Flyout once. This does not cause any exceptions, only if my home page is not instantiated at all.

Explanation:
If I open the app on the Home screen, log out (go to login), log in again, the exception does not occur even when using

Application.Current.Windows[0].Page = page;

Because the HomePage was already created one time. This seems like just a coincidence, but it was noticed.

I can't say that this is what is causing the error.

I confess that this situation is making me lose my hair.

I am available for any information and help needed.

kubaflo · 2025-05-17T14:43:12Z

@PureWeen can you please /azp, so that @MateusMiotto can try if this PR fixes it

PureWeen · 2025-05-20T20:35:06Z

@PureWeen can you please /azp, so that @MateusMiotto can try if this PR fixes it

@MateusMiotto where you able to try the nugets from @kubaflo 's PR?

MateusMiotto · 2025-05-20T20:46:15Z

This fix is avaliable in any published version?

kubaflo · 2025-05-20T22:34:46Z

This fix is avaliable in any published version?

@MateusMiotto No, it isn't. We would like you to test this pr: #29564 according to these docs: https://github.com/dotnet/maui/wiki/Testing-PR-Builds

It is because we want to know if the changes fix your crash since you did not attach any repro and we cannot reproduce it

MateusMiotto · 2025-05-21T12:40:17Z

I followed the tutorial link and spent a few hours today to test this fix and it worked fine, the exception doesn't happen anymore.

MateusMiotto added the t/bug Something isn't working label May 15, 2025

PureWeen added high It doesn't work at all, crashes or has a big impact. platform/iOS s/needs-info Issue needs more info from the author area-navigation NavigationPage labels May 15, 2025

dotnet-policy-service bot added s/needs-attention Issue has more information and needs another look and removed s/needs-info Issue needs more info from the author labels May 16, 2025

kubaflo linked a pull request May 17, 2025 that will close this issue

[iOS] System.NullReferenceException at NavigationRenderer.SetStatusBarStyle() #29564

Open

PureWeen added the potential-regression This issue described a possible regression on a currently supported version., verification pending label May 20, 2025

PureWeen added this to the .NET 9 Servicing milestone May 20, 2025

anandhan-rajagopal added s/verified Verified / Reproducible Issue ready for Engineering Triage s/triaged Issue has been reviewed and removed s/needs-attention Issue has more information and needs another look labels May 22, 2025

mattleibow added platform/ios and removed platform/iOS labels May 23, 2025

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System.NullReferenceException at NavigationRenderer.SetStatusBarStyle() #29535

System.NullReferenceException at NavigationRenderer.SetStatusBarStyle() #29535

MateusMiotto commented May 15, 2025 •

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MateusMiotto commented May 16, 2025

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kubaflo commented May 17, 2025

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MateusMiotto commented May 21, 2025

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System.NullReferenceException at NavigationRenderer.SetStatusBarStyle() #29535

System.NullReferenceException at NavigationRenderer.SetStatusBarStyle() #29535

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Description

Steps to Reproduce

Link to public reproduction project repository

Version with bug

Is this a regression from previous behavior?

Last version that worked well

Affected platforms

Affected platform versions

Did you find any workaround?

Relevant log output

similar-issues-ai bot commented May 15, 2025

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MateusMiotto commented May 16, 2025

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kubaflo commented May 17, 2025

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PureWeen commented May 20, 2025

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MateusMiotto commented May 20, 2025

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kubaflo commented May 20, 2025

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MateusMiotto commented May 21, 2025

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MateusMiotto commented May 15, 2025 •

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PureWeen commented May 15, 2025 •

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