Exception: NullReferenceException on saving a PPTX file with ComboBox (C# .NET)

Aspose.Slides for .Net throws a NullReferenceException when trying to save the attached .pptx file input.zip (22.8 KB) as .ppt using the following code:

var input = @"<...>\input.pptx";
var presentation = new Presentation(input);
presentation.Save(input + "_save.ppt", SaveFormat.Ppt);

Observed this on versions 19.11.0 and 18.10.0 as well.

The file was created using Ms PowerPoint 2016 by simply adding a ComboBox content control to the first slide of a new presentation and leaving it empty.

Thanks for any help!

@arnoldbeilandevozon,

I have worked with the file shared by you and have been able to observe the issue specified. An issue with ID SLIDESNET-41632 has been created in our issue tracking system to further investigate and resolve the issue. We will share the notification with you once issue will be fixed.