I have worked with the presentation file shared by you using Aspose.Slides for Java 7.1.1 on my end and have not been able to reproduce the issue specified. For your convenience, I have shared the generated PDF as well. Please try using the specified version on your end.
I’ve re-tested with the latest version. I no longer get the error if I run a plain conversion.
I do get an error with some other operations I’m performing such as removing header and footer text. I will need to check what of these changes could be causing this problem.
You may please perform verification on your end. If there is an issue then please share the sample code along with the source presentation with us to reproduce the issue on my end. Please also share the environment details with us.