dotnet/wpf · error · NotSupportedException

SR.JumpList_CantCallUnbalancedEndInit

Error message

SR.JumpList_CantCallUnbalancedEndInit

What it means

JumpList uses the ISupportInitialize two-phase pattern: EndInit commits (and optionally auto-applies) the list. EndInit throws NotSupportedException when there is no matching BeginInit in progress (_initializing != true), because committing an uninitialized list breaks the protocol.

Solutions

1. Ensure every EndInit() is paired with exactly one prior BeginInit() on the same instance.
2. Wrap BeginInit/EndInit in try/finally only when BeginInit succeeded; otherwise skip EndInit.
3. Track initialization state yourself with a flag before calling EndInit.
4. Use Apply() alone if you do not need two-phase initialization.

Example fix

// before
jumpList.EndInit(); // no BeginInit was called -> NotSupportedException
// after
jumpList.BeginInit();
jumpList.JumpItems.Add(new JumpTask { ... });
jumpList.EndInit();

bool inInit = false;
void SafeEndInit(JumpList jl)
{
    if (!inInit) throw new InvalidOperationException("EndInit without BeginInit");
    jl.EndInit();
    inInit = false;
}

try { jumpList.EndInit(); }
catch (NotSupportedException ex) { Log.Warn("Unbalanced EndInit on JumpList", ex); }

When it happens

Trigger: Calling EndInit() on a JumpList that never had BeginInit() called, or after EndInit()/Apply() already completed the cycle.

Common situations: Cleanup code that calls EndInit in a finally block even when BeginInit threw; copying init code from a class that does not require BeginInit; calling EndInit twice.

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

• SR.JumpList_CantApplyUntilEndInit
• SR.JumpList_CantNestBeginInitCalls
• By default, ToolTip property does not support ToolTip…
• Cannot convert from type.
• Cannot convert to type.

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/958a606a2c73efea. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Shell/JumpList.cs:368

            if (!IsUnmodified)
            {
                throw new InvalidOperationException(SR.JumpList_CantNestBeginInitCalls);
            }

            _initializing = true;
        }

        /// <summary>
        /// Signal the end of initialization of this JumpList.  If it is attached to the current Application, apply the contents of the jump list.
        /// </summary>
        /// <remarks>
        /// Calls to EndInit must be paired with calls to BeginInit.
        /// </remarks>
        public void EndInit()
        {
            if (_initializing != true)
            {
                throw new NotSupportedException(SR.JumpList_CantCallUnbalancedEndInit);
            }

            _initializing = false;

            // EndInit only implicitly applies the list if the current Application has been set as an attached property.
            ApplyFromApplication();
        }

        #endregion

        /// <summary>
        /// Get the AppUserModelId for the running process.
        /// </summary>
        /// <remarks>
        /// This is a Shell property that currently is only used as part of a heuristic
        /// for what taskbar item an HWND should be associated with, e.g. you can put
        /// windows from multiple processes into the same group, or you can prevent glomming
        /// of HWNDs that would otherwise be shown together.

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