This exception seems to be related to AES algorithm PaddingMode property. 

This exception seems to be caused because the stream is not decrypted correctly and the stream data is corrupted. For instance when the stream is with FlateDecode filter the exception is InvalidDataException with message "Unknown compression method".

This exception is thrown because there is field name with special characters which are incorrectly modified during the recalculation process of widget appearances. This exception is thrown in the internal RecalculateMissingAppearances method or in RecalculateWidgetAppearancesOld method.

Loading page with a lot of text takes several minutes which is unacceptable. This performance issue is caused by class GlypInfoFactory, which caches the glyph information.

Available in LIB Version 2017.3.1225.

For some fonts the issue is present. Some of them are:

KozGoPro-Medium

KozMinPro-Regular

KozGoPro-Bold

Enable the customers to directly save the document inside PdfViewer to a file or a stream.

Available in LIB Version 2017.3.1225.

The Ò symbol is not found in the encoding as is rendered as a ".notdef" glyph.

Available in LIB Version 2017.3.1127.

This may result in inversed transparency issue when rendering images with ImageMask.

Fix available in LIB Version 2017.3.1120.

Currently, the implementation relies on the fact that the previous cross-reference value of a stream object is always a stream object. Instead during the cross-reference recursion, we should check on each step whether the previous cross-reference item is table or stream.

Fix available in LIB Version 2017.3.1120.

When a page is rotated its annotations are not positioned correctly. 

The images are loaded asynchronously and when scrolling too fast, the loader might fail to load an image if it is bigger.

The appearance of such invisible annotation is not imported property and the viewer is trying to recalculate it in an infinite recursion which causes the StackOverflowException.

Fix available in LIB Version 2017.3.1009.

The UserDict collection is not parsed and the procedures for the operators are unavailable. The exception is thrown while trying to read the font file of the Univers and Univers Bold fonts.

Internally, an ArgumenNullException is thrown, which results in missing content when the document is shown in RadPdfViewer.

Default DctDecode implementation uses System.Windows.Media.Imaging.BitmapImage in order to get the image pixels. However, when the image uses some complex colorspace (for instance Separation based on CMYK) the BitmapImage is initialized with a different format and we use System.Windows.Media.Imaging.FormatConvertedBitmap in order to get the pixels in CMYK colorspace. There seems to be some issue with these calculations as the resulting image has incorrect pixels.

WORKAROUND: You may inherit DctDecode class in order to implement custom decoder and call DecodeWithJpegDecoder method from the base class as mentioned in the note of this documentation article:

http://docs.telerik.com/devtools/wpf/controls/radpdfviewer/customization-and-extensibility/customize-pdf-rendering

A sample implementation of these custom decoder may be seen below:

public class CustomDctDecode : DctDecode
{
    public override byte[] Decode(PdfObject decodedObject, byte[] inputData, DecodeParameters parms)
    {
        return DecodeWithJpegDecoder(inputData);
    }
}

When annotations have annotation flag Print they should be visualized when printing the document. Usually, Widget annotations have such flag and currently RadPdfViewer does not print them at all.

Available in LIB Version 2017.3.918.

NullReferenceException is thrown when importing a document with AcroForm referencing a missing object for fields collection. This is a regression as the same document will be imported without a problem in previous versions of RadPdfViewer as the AcroForm object would be entirely skipped.

The current implementation relies on the graphic state color to be always SolidColorBrush. However, it may be other color type and InvalidCastException is thrown. This results in missing content.

Available in LIB version 2017.1.410.

Decode array for image masks with DeviceGray color space is not respected, and always the default array of [0 1] is used for visualization. When the mask is encoded with [1 0], the mask is applied inversed, making the wrong pixels transparent. This may lead to images becoming invisible.

Fix available in LIB Version 2017.3.1120.

Due to excessive memory consumption when decoding images, OutOfMemoryException can be thrown when viewing documents with large images inside them. 

Workarounds: 
- Set ExtensibilityManager.MaxImageSize = null. This will skip one resizing step, and could be beneficial in documents containing few large images.
- Use 64-bit process for the client application. This allows the process to consume much more memory. Note that starting 64-bit process while debugging can be tricky, as described in this blog post: https://weblog.west-wind.com/posts/2016/Dec/19/Visual-Studio-Debugging-and-64-Bit-NET-Applications.

Available in R1 2018 Official release version.

The PdfViewer won't load a document from PdfDocumentSource created from Uri and the ReadOnDemand option.
Here is an example: new PdfDocumentSource(new Uri("webaddress/somefile.pdf"), FormatProviderSettings.ReadOnDemand);

Available in LIB Version 2017.1.130