"Specified Method Is Not Supported" Error when Saving a Presentation to a Stream

Aspose.Slides Product Family
1

While saving a Presentation using an OutputStream we have started receiving a Specified method is not supported error. I recently updated to version 25.1.0.0 with the previous version working correctly. If I change to save presentation to file using a string instead of the OutputStream it saves fine so it must be something with the stream. The code where the issue arises is below with OutputFileName a string that is defined by the page calling the method.

Page.Response.Clear();
Page.Response.Charset = "";
Page.Response.ContentType = "application/vnd.openxmlformats-officedocument.presentationml.presentation";
Page.Response.AppendHeader("content-disposition", "attachment; filename=\"" + OutputFileName + ".pptx\"");

Aspose.Slides.Presentation.Save(Response.OutputStream, Aspose.Slides.Export.SaveFormat.Pptx);
2

@shepkapit

The error you are encountering, “Specified method is not supported,” when trying to save a presentation to an OutputStream may be related to the way the stream is being handled or the specific format you are trying to save in.

Here are a few steps you can take to troubleshoot and resolve the issue:

  1. Check Stream Type: Ensure that the OutputStream you are using is compatible with the Save method. The stream should be writable and properly initialized.

  2. Use Correct Save Method: Make sure you are using the correct overload of the Save method. For saving to a stream, you should use:

    presentation.Save(stream, SaveFormat.Pptx);

    This method saves the entire presentation to the specified stream in the PPTX format.

  3. Stream Initialization: Ensure that the stream is properly initialized before passing it to the Save method. For example:

    using (FileStream stream = new FileStream("output.pptx", FileMode.Create))
{
    presentation.Save(stream, SaveFormat.Pptx);
}

  4. Check for Updates: Since you mentioned that the issue started after updating to version 25.1.0.0, it might be worth checking the release notes or documentation for any breaking changes or known issues related to saving presentations.

  5. Test with a Simple Example: Try running a minimal example to isolate the issue. For instance:

    using (Presentation presentation = new Presentation())
{
    // Add a simple shape or text
    var slide = presentation.Slides[0];
    slide.Shapes.AddAutoShape(ShapeType.Rectangle, 50, 50, 200, 100);
    
    using (FileStream stream = new FileStream("output.pptx", FileMode.Create))
    {
        presentation.Save(stream, SaveFormat.Pptx);
    }
}

If the problem persists after trying these steps, consider reverting to the previous version of the library that was working correctly, or reach out to Aspose support for further assistance.

For more detailed information on saving presentations, you can refer to the official documentation on saving presentations to streams here and check the examples provided for saving presentations in different formats.

If you have any further questions or need additional help, feel free to ask!