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Concatenate returns Trailer is not found exception

We are using PdfFileEditor.Concatenate to merge PDFs and occasionally we get a "Trailer is not found" exception: Trailer is not found. Inner Exception: Stack Trace: at Aspose.Pdf.Kit.PdfFileEditor.x4c788cf08ce3235c(String[] xec232eb93dd022a7)

Can you tell me what, in general, that means? I'm trying to get some more details from our development team on the exact code, but here's what I have so far:
We are using C# .NET 4.0, Aspose.PDF.Kit version and the following code:

PdfFileEditor pdfEditor = new PdfFileEditor();

pdfEditor.Concatenate(arrInputFileNames, outputFilePath);

We are having this problem with a subset of PDFs and I can send you one if it would help, though I don't want it publicly accessible, so I'm not sure if I should attach it to this post (sorry, I'm new to your forum).

Please let me know what you think and/or let me know what other information I should request from our development team. Thanks.


Hi Joe,

Thank you for considering Aspose.Pdf.

First of all, as you are using an older version of Aspose.Pdf.Kit for .NET, I would like to inform you that Aspose.Pdf for .NET and Aspose.Pdf.Kit for .NET have been merged into a single product and Aspose.Pdf.Kit for .NET has been discontinued as a separate product. All the features of Aspose.Pdf.Kit for .NET are available under Aspose.Pdf.Facades namespace of Aspose.Pdf for .NET v6.x. Please download and try the latest version of Aspose.Pdf for .NET v6.6 and check if you still face any issue. You can check the following documentation links to migrate your code from Aspose.Pdf.Kit for .NET to the new merged Aspose.Pdf for .NET.


If you still face any issue, please share your template file with us and we will check the issue and get back to you. As your template file has some confidential data, so you may make this thread as private by checking “Keep this post as private” checkbox at the bottom when replying to the post, this way only Aspose staff and you would be able to see your attachments.

Please feel free to contact support in case you need any further assistance.

Sorry for the inconvenience,