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Form.FlattenField throws an exception

Dear experts,

I am working on a legacy VB.Net application that uses Aspose.Pdf to fill a pdf document. It used to work previously, but recently I updated the Aspose.Pdf to version 18.8.0, and now it throws an exception on the same document that worked before the update:

                        Case "PRICEHEADING2"
                        inForm.FillField(tableField, strDiscPriceCol)

FillField() works, but FlattenField() throws an exception:
Provided field name ‘CUSTOMER_PRICEHEADING2’ doesn’t designate form field.

CUSTOMER_PRICEHEADING2 does exist in the document. It is present on multiple pages, and is expected to be populated with the same data and to be flattened everywhere.

Please advise.


Thank you for contacting support.

Would you please share a narrowed down and self-contained code snippet along with sample PDF file so that we may try to reproduce and investigate it. Please also specify which version works fine. Before sharing requested data, please ensure using Aspose.PDF for .NET 18.9.1 in your environment.


Previously, Aspose.Pdf version and Aspose.Pdf.Kit version were used, and it worked.
Are you sure that 18.9.1 may fix my issue? If not, I would prefer not to make an update right now, as the version I use is pretty recent.

I believe that any pdf file with duplicate fields would give the same result. Somebody reported it here:

If you give me your email address, I can send you the file, as I would prefer not to show it to everybody.


The thread you are referring to is quite old and the issue was logged as a file specific problem. Since the support is provided on basis of latest available version so we need to test it with latest version if the issue exists or not. Therefore, we have requested for sample code and a PDF file to reproduce and investigate it in our environment.

I have sent you the pdf in a private message.


Thank you for sharing the file.

Please also share a Self Contained and Correct (Compilable) code snippet to reproduce the problem. We will investigate and then share our findings with you soon.

Here is my code with the new Aspose version:

Imports Aspose.Pdf.Facades

Module Module1

Sub Main()
    Dim inForm As Form
    Dim fieldName As String = "CUSTOMER_PRICEHEADING2"
    Dim destFilePath As String = "F:\DataEntry\AsposeResult.pdf"

    inForm = New Form("F:\DataEntry\DS-692.0-1217_2018 Domestic Pricebook-504k34kqa22ipwld0ujsjlpe.pdf")
    inForm.FillField(fieldName, "Dummy Data")

    ' Make this field un-editable


End Sub

End Module

With this version, inForm.FlattenField(fieldName) throws an exception:

: ‘Provided field name ‘CUSTOMER_PRICEHEADING2’ doesn’t designate form field.’


Thank you for sharing requested data.

We have been able to reproduce the issue in our environment. A ticket with ID PDFNET-45374 has been logged in our issue management system for further investigation and resolution. The ticket ID has been linked with this thread so that you will receive notification as soon as the ticket is resolved.

We are sorry for the inconvenience.

Thank you!
May I ask, where your issue management system can be seen (just in case)?
Also, about how long can it take?



We are afraid you may not access our internal issue tracking system (JIRA). However, you may make a request for issue progress in this thread or you can view issue status from bottom left column, under this thread. Moreover, please note that the issue has been logged under free support model and will be resolved under first come first serve policy which can take some months.

Furthermore, we also offer paid support model where issues are resolved on urgent basis and have priority over the issues logged under free support model. You may check our Paid Support options for your reference.


Could you please tell how much it would cost?



For any sales related query, kindly create a post over Purchase Forum and we will share the details with you. Or you can find contact details for such inquiries, over Contact Us page.

I am surprised that after we purchased this non-functional product, we have to pay for being able to finally use it.


Please note that we offer a free 30 day temporary license to let our customers test the API if it meets their requirements before paying for it. Many customers are using the API without any issue as it fulfills their requirements. However, there might be some issues which could be scenario or file specific. We always value concerns of our customers and resolve each issue reported to us. But the resolution time depends on the model issues are logged under. We appreciate your comprehension in this regard.

We are sorry for the inconvenience.

I just downgraded Aspose.Pdf package to version 10.2.0 that we use on our legacy application. It gives the same error! I wonder why it works for the same file in the legacy application… Don’t you have any clue by any chance?


We are afraid we may not have any clue about that difference. We will take care of your concerns with latest version of the API as respective ticket has been logged in our issue management system. We will get back to you once any significant information is available in this regard.

Could you please give me any update on this issue? Has it been resolved?



Thank you for getting back to us.

We would like to update you that PDFNET-45374 is scheduled for upcoming week. We will let you know as soon as some significant updates will be available. We appreciate your patience and comprehension in this regard.


Anything new on this issue?


We are afraid that PDFNET-45374 has not been investigated yet owing to some critical and higher priority issues. However, we have recorded your concerns and will schedule it as soon as we can. Please spare us some more time.