{"record":{"id":"b4bbd182bbc5401f","repo":"PrismLibrary/Prism","slug":"the-region-does-not-contain-the-specified-view","errorCode":null,"errorMessage":"The region does not contain the specified view.","messagePattern":"The region does not contain the specified view\\.","errorType":"exception","errorClass":"ArgumentException","httpStatus":null,"severity":"error","filePath":"src/Maui/Prism.Maui/Navigation/Regions/Region.cs","lineNumber":352,"sourceCode":"    /// Removes all views from the region.\n    /// </summary>\n    public void RemoveAll()\n    {\n        foreach (var view in Views)\n        {\n            Remove(view);\n        }\n    }\n\n    private ItemMetadata GetItemMetadataOrThrow(object view)\n    {\n        if (view == null)\n            throw new ArgumentNullException(nameof(view));\n\n        var itemMetadata = ItemMetadataCollection.FirstOrDefault(x => x.Item == view);\n\n        if (itemMetadata == null)\n            throw new ArgumentException(Resources.ViewNotInRegionException, nameof(view));\n\n        return itemMetadata;\n    }\n\n    internal static int DefaultSortComparison(object x, object y)\n    {\n        if (x == null)\n        {\n            if (y == null)\n            {\n                return 0;\n            }\n            else\n            {\n                return -1;\n            }\n        }\n        else","sourceCodeStart":334,"sourceCodeEnd":370,"githubUrl":"https://github.com/PrismLibrary/Prism/blob/358118cd640d9a22ff8cf21c8ad197fa038b7990/src/Maui/Prism.Maui/Navigation/Regions/Region.cs#L334-L370","documentation":"Region.GetItemMetadataOrThrow throws ArgumentException (Resources.ViewNotInRegionException, param 'view') when the view object is not tracked in the region's ItemMetadataCollection. You can only Remove/deactivate views that were previously Added to this region.","triggerScenarios":"Calling region.Remove(view) for a view instance that was never added to this region, or that was already removed; adding the view to a different region than the one you remove from.","commonSituations":"Removing views across region instances (stale region reference); double-remove after RemoveAll; assumptions that a view registered globally lives in a specific region.","solutions":["Verify the view exists in the region first: region.Views.Contains(view) before calling Remove.","Ensure the view was added to THIS region instance (compare RegionManager.RegionNames).","Make Remove idempotent on your side by tracking removals or wrapping in a Contains check.","Use RemoveAll() when you intend to clear everything."],"exampleFix":"// before\nregion.Remove(view); // may throw if absent\n\n// after\nif (region.Views.Contains(view))\n    region.Remove(view);","handlingStrategy":"validation","validationCode":"if (view == null || !region.Views.Contains(view)) return;","typeGuard":"static bool BelongsToRegion(IRegion region, object view) => view != null && region.Views.Contains(view);","tryCatchPattern":"try { region.Remove(view); } catch (ArgumentException ex) { logger.LogWarning(ex, \"View not part of region {Region}\", region.Name); }","preventionTips":["Check region.Views.Contains(view) before Remove","Keep a 1:1 mapping between views and the region they were added to","Track removals to make cleanup idempotent and avoid double-remove"],"tags":["prism","maui","regions","resource-not-found"],"backgroundTag":"resource-not-found","analyzedSha":"358118cd640d9a22ff8cf21c8ad197fa038b7990","analyzedAt":"2026-09-15T15:00:31.079Z","contentChangedAt":"2026-09-15T15:00:31.079Z","schemaVersion":2},"datasetVersion":"2026-09-23T08:17:48.524Z"}