dotnet/wpf · error · InvalidOperationException

SR.Image_EndInitWithoutBeginInit

Error message

SR.Image_EndInitWithoutBeginInit

What it means

EndInit finalizes initialization and may only run inside an open BeginInit/EndInit pair. If EndInit is called without a prior BeginInit (IsInInit == false), WPF throws InvalidOperationException with SR.Image_EndInitWithoutBeginInit.

Solutions

  1. Always pair EndInit with a preceding BeginInit in the same scope
  2. Guard EndInit with a check of the init state, or track it with your own flag before calling
  3. If you construct via constructor, do not call BeginInit/EndInit at all — set properties and use the image directly

Example fix

// before
var img = new BitmapImage();
img.EndInit(); // throws: no BeginInit
// after
var img = new BitmapImage();
img.BeginInit();
img.UriSource = new Uri(path);
img.EndInit();
Defensive patterns

Strategy: validation

Validate before calling

bool canEndInit(BitmapImage img, bool beginWasCalled) => beginWasCalled; // only EndInit after your own BeginInit

Try / catch

bool begun = false;
try { if (begun) { img.EndInit(); begun = false; } }
catch (InvalidOperationException) { /* EndInit without BeginInit */ }

Prevention

When it happens

Trigger: Calling EndInit() on a BitmapImage that never had BeginInit called, or calling it twice after the first EndInit already reset _inInit, or after construction via constructor instead of the ISupportInitialize pattern.

Common situations: Mixing the BitmapImage(uri) constructor with a stray EndInit call; defensive cleanup code that calls EndInit in a finally block even when init was never started; XAML loader path combined with manual init calls.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/54643a7d6c82c36a. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/Imaging/BitmapInitialize.cs:32

        public BitmapInitialize()
        {
        }

        public void BeginInit()
        {
            if (IsInitAtLeastOnce)
                throw new InvalidOperationException(SR.Format(SR.Image_OnlyOneInit, null));

            if (IsInInit)
                throw new InvalidOperationException(SR.Format(SR.Image_InInitialize, null));

            _inInit = true;
        }

        public void EndInit()
        {
            if (!IsInInit)
                throw new InvalidOperationException(SR.Format(SR.Image_EndInitWithoutBeginInit, null));

            _inInit = false;
            _isInitialized = true;
        }

        public void SetPrologue()
        {
            if (!IsInInit)
            {
                throw new InvalidOperationException(SR.Format(SR.Image_SetPropertyOutsideBeginEndInit, null));
            }
        }

        public bool IsInInit
        {
            get
            {
                return _inInit;

View on GitHub (pinned to 81131a70a4)