Mono Runtime Attempts to Load Missing pt-BR Satellite Assemblies Causing Initialization Lag in MAUI App

[BrundhaVelusamy]

We’re encountering a recurring issue when running our .NET MAUI app on devices with pt-BR (Portuguese - Brazil) UI settings. Our project is defined with neutral language as en-US, and we do not include localized resource assemblies for pt-BR.

However, during InitializeComponent() execution, the Mono runtime attempts to load satellite assemblies like:

pt-BR/Syncfusion.Maui.Toolkit.resources.dll  
pt/Syncfusion.Maui.Toolkit.resources.dll

These assemblies do not exist in our app package, and we see repeated log entries like:

[monodroid-assembly] open_from_bundles: failed to load bundled assembly pt-BR/Syncfusion.Maui.Toolkit.resources.dll   
[monodroid-assembly] open_from_update_dir: assembly file DOES NOT EXIST

This causes noticeable lags and timeouts during initialization, even though the fallback to neutral resources eventually works.

We’ve tried setting:
CultureInfo.DefaultThreadCurrentUICulture = new CultureInfo("en-US");

But it didn’t resolve the issue.

• Is there a recommended way to suppress or prevent these unnecessary satellite assembly load attempts?
• Is this expected behavior in Debug builds, and will it be optimized in Release builds?
• Could this be related to how MAUI or Mono handles localization fallback?

Any insights or suggestions from the community would be greatly appreciated!

Thanks in advance.

[ghost]

@BrundhaVelusamy I think you will get better support for this in the Syncfusion dedicated discussions. I have very good experience by their support. It was a similar "not found" thing, everything worked, just the error was flodding error log.

CoPilot found this two resources, I do not know if this helps.

• https://learn.microsoft.com/en-us/dotnet/core/extensions/create-satellite-assemblies
• https://learn.microsoft.com/en-us/dotnet/core/dependency-loading/loading-resources

[eyadon]

@BrundhaVelusamy We ran into this after upgrading to VS 2026 - it took 3 minutes for the main page of the app to load...
It didn't happen on release builds, only debug.
After a lot of experimentation, what finally worked was turning off "Enable new .NET Mono debugger for MAUI apps" under Preview Features in the settings.