PrismLibrary/Prism · error · InvalidOperationException

Deactivation is not possible in this type of region.

Error message

Deactivation is not possible in this type of region.

What it means

AllActiveRegion keeps every added view active and does not support deactivation. Its Deactivate override unconditionally throws InvalidOperationException (Resources.DeactiveNotPossibleException). Deactivation is only meaningful in SingleActiveRegion-style regions.

Solutions

1. Remove or conditionalize the Deactivate call — check the region type before deactivating (e.g. only call Deactivate when region is SingleActiveRegion)
2. Use region.Remove(view) if the intent is to remove the view from the region instead of deactivating it
3. If activation control is needed, change the region type/behavior for that control to a single-active region

Example fix

// before
region.Deactivate(view);

// after
if (region is SingleActiveRegion)
    region.Deactivate(view);
else
    region.Remove(view);

bool canDeactivate = region is SingleActiveRegion;
if (!canDeactivate) { /* skip or remove the view instead */ }

bool SupportsDeactivation(IRegion region) => region is SingleActiveRegion;

try { region.Deactivate(view); }
catch (InvalidOperationException) { /* all-active region: use Remove instead */ }

When it happens

Trigger: Calling IRegion.Deactivate(view) on a region created by AllActiveRegion — e.g. region.Deactivate(someView) or navigation logic that attempts to deactivate views in a region adapted with an all-active adapter (like ContentPresenter/LayoutView regions configured as AllActiveRegion).

Common situations: Shared navigation/viewmodel code calling Deactivate on any region regardless of type; switching a region's adapter/behavior from single-active to all-active and existing deactivation calls now failing; navigation frameworks probing deactivation support.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Layout 's Children property is not empty. This control is…
• regionName
• regionTarget
• The object must be of type
• Mapping with the given type is already registered

AI-assisted analysis of PrismLibrary/Prism@358118cd64 (2026-09-15). Data as JSON: /api/errors/d5f77e0bcbd58351. Report an issue: GitHub.

Appendix: source

Thrown at src/Maui/Prism.Maui/Navigation/Regions/AllActiveRegion.cs:32

    public AllActiveRegion(IRegionNavigationService regionNavigationService)
        : base(regionNavigationService)
    {
    }

    /// <summary>
    /// Gets a readonly view of the collection of all the active views in the region. These are all the added views.
    /// </summary>
    /// <value>An <see cref="IViewsCollection"/> of all the active views.</value>
    public override IViewsCollection ActiveViews => Views;

    /// <summary>
    /// Deactivate is not valid in this Region. This method will always throw <see cref="InvalidOperationException"/>.
    /// </summary>
    /// <param name="view">The view to deactivate.</param>
    /// <exception cref="InvalidOperationException">Every time this method is called.</exception>
    public override void Deactivate(object view)
    {
        throw new InvalidOperationException(Resources.DeactiveNotPossibleException);
    }
}

View on GitHub (pinned to 358118cd64)