Problem using PDF..Flatten();

HI I need assistance, I’m trying to flatten some pdfs, but I’m getting this error

System.NullReferenceException
HResult=0x80004003
Message=Object reference not set to an instance of an object.
Source=Aspose.PDF
StackTrace:
at Aspose.Pdf.Document.#=zQ9v7J4TVhWZD(Page #=zRSpRhUg=)
at Aspose.Pdf.Document.#=zN4O_06M=()
at Aspose.Pdf.Document.Flatten(FlattenSettings flattenSettings)
at Aspose.Pdf.Document.Flatten()
at Program.$(String[] args) in C:\Source\repos\test\TestConsoleApp\TestConsoleApp\Program.cs:line 95

That is not a very helpful error, the pdf is a valid PDF but I don’t know what it’s the problem.

Regards.

@Luis_Garcia
Thank you for contacting support.
Would you please share some more details like sample files and the code snippet along with the OS and Lib versions used (Aspose.Pdf versions, framework versions, etc.)