Currently, RadPdfViewer offers the DataError event which is purposed to handle errors during the import process. However, if there are problematic pages that are rendered in the viewer at a later moment after the document is already imported, the viewer doesn't offer a suitable way for handling such problematic moments even though the PdfProcessing library throws one of its exceptions. 

The exact client's case is loading a PDF document which contains images requiring JPX Decoder which is currently not supported. Even though the PdfProcessing library throws internally the following error, the RadPdfViewer control doesn't throw the DataError event with the respective error:

Telerik.Windows.Documents.Fixed.Exceptions.NotSupportedFilterException: 'JPXDecode is not supported.'

The problem I'm trying to solve is that users do not know that the original document may not be what they are seeing in the viewer when there are layers.    

A property that indicates that a document has layers would allow the system to refuse to open the document.

RadPdfViewer can not display annotated PDF file
 Kindly,i used VintaSoft SDk to Annotate PDF File, File is annotated successfully and i can open it with Adobe Reader and see annotations is added to it
 but while i try to view annotated PDF file using RadPDFViewer File will displayed without annotations ,only original content displayed.
Kindly find my attached AnnotatedPDFfile To be loaded in RadPDfViewer

The issue is reproducible only on Windows XP. On newer versions of windows, the images are rendered as expected.

WORKAROUND: You may try implementing custom filter that handles the CMYK scenario. How to implement custom DCTDecode filter is described in this documentation article:
https://docs.telerik.com/devtools/winforms/pdfviewer/customize-and-extensibility/customize-pdf-rendering

Is there a way to load this RadFixedDocument into a RadPdfViewer without writing the document to a file first and then loading it in the viewer?

Workaround:

You can achieve the desired functionality by exporting the RadFixedDocument to a MemoryStream instead of a file in the file system and then load it in the PdfViewer: 

RadFixedDocument document = CreateRadFixedDocument();

PdfFormatProvider pdfFormatProvider = new PdfFormatProvider();
Stream ms = new MemoryStream();
pdfFormatProvider.Export(document, ms);

radPdfViewer1.LoadDocument(ms);

According to PDF format specification, there are three valid encoding name values (MacRomanEncoding, MacExpertEncoding and WinAnsiEncoding). There are documents that instead of skipping the optional Encoding property, are writing invalid /NULL name value in the font dictionary. Currently, in this invalid document scenario RadPdfViewer throws and catches Exception and this results in missing text content. 

We may handle this invalid document scenario by ignoring the invalid Encoding value.

Add functionality for a PDF form filler that supports text auto-sizing/shrinking like Adobe:

Hi,

Is there a way to get version and producer metadata from imported PDF files? 

Here is how it looks in AdobeReader

Thanks in advance,