Print() Method Hangs in WPF and WinForms

Curtis Chau

Updated: July 6, 2026

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  # Print() Method Hangs in WPF and WinForms When you call the synchronous `Print()` method in a WPF or WinForms application, the method is invoked but never completes. The call hangs indefinitely, blocking the thread and freezing the UI even when the print job itself is valid. ```csharp IronPrint.Printer.Print("Test print"); // Hangs here ``` This is expected behavior. `Print()` is intentionally synchronous and blocks the calling thread until the print job completes, so calling it from a WPF or WinForms UI thread freezes the UI. ## Solution Call the asynchronous API instead of the synchronous one. ```csharp await IronPrint.Printer.PrintAsync("Test print"); ``` `PrintAsync()` moves the print operation off the blocking path, so the job completes and the UI stays responsive in both WPF and WinForms. ## Best Practices - **Prefer async APIs:** reach for `PrintAsync()` in WPF and WinForms to avoid UI thread deadlocks. - **Never block on the main thread:** avoid `.Result` and `.Wait()` against an async call. - **Offload long-running I/O:** keep printing and other external work on background or async tasks.

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When you call the synchronous Print() method in a WPF or WinForms application, the method is invoked but never completes. The call hangs indefinitely, blocking the thread and freezing the UI even when the print job itself is valid.

IronPrint.Printer.Print("Test print"); // Hangs here

IronPrint.Printer.Print("Test print"); // Hangs here

This is expected behavior. Print() is intentionally synchronous and blocks the calling thread until the print job completes, so calling it from a WPF or WinForms UI thread freezes the UI.

Solution

Call the asynchronous API instead of the synchronous one.

await IronPrint.Printer.PrintAsync("Test print");

await IronPrint.Printer.PrintAsync("Test print");

PrintAsync() moves the print operation off the blocking path, so the job completes and the UI stays responsive in both WPF and WinForms.

Best Practices

• Prefer async APIs: reach for PrintAsync() in WPF and WinForms to avoid UI thread deadlocks.
• Never block on the main thread: avoid .Result and .Wait() against an async call.
• Offload long-running I/O: keep printing and other external work on background or async tasks.

Curtis Chau

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Technical Writer

Curtis Chau holds a Bachelor’s degree in Computer Science (Carleton University) and specializes in front-end development with expertise in Node.js, TypeScript, JavaScript, and React. Passionate about crafting intuitive and aesthetically pleasing user interfaces, Curtis enjoys working with modern frameworks and creating well-structured, visually appealing manuals.

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