If HTML document is imported, and it contains image with invalid URL, then the image is imported with this URL in the document model. On subsequent export to Docx, the library tries to download the image data, which throws WebException. Instead, the image should be replaced with generic 'error' image.

Workaround: Manually test the image URL for correctness on HTML import, and replace the data:

        static void Main(string[] args)
        {
            HtmlFormatProvider htmlFormatProvider = new HtmlFormatProvider();
            htmlFormatProvider.ImportSettings.LoadFromUri += (sender, e) =>
            {
                if (!IsValid(e.Uri))
                {
                    e.SetData(File.ReadAllBytes("no-image.png"));
                }
            };
        }

        private static bool IsValid(string uri)
        {
            try
            {
                using (WebClient client = new WebClient())
                {
                    client.DownloadData(uri);
                }
            }
            catch (WebException)
            {
                return false;
            }

            return true;
        }

WinAnsiEncoding it is imported as StandardEncoding since WinAnsiEncoding is still not implemented in RadPdfProcessing. 

The empty lines are not converted properly from RTF to HTML

Workaround: 

Special chars (åäö) with PdfFormatProvider wont work.

Project submitted!

    public void SpecialCharsTest()
        {
            RadFlowDocument document = new RadFlowDocument();

            RadFlowDocumentEditor editor = new RadFlowDocumentEditor(document);

            editor.InsertText("Before text");
            editor.InsertText("åäö ÅÄÖ ☕"); // This line will not appear in the pdf 
            editor.InsertText("After text");
            using (Stream output = new FileStream("specialCharTest.pdf", FileMode.OpenOrCreate))
            {
                PdfFormatProvider provider = new PdfFormatProvider();
                provider.Export(document, output);
            }
        }

Special characters wont work :-/

When merging files that contain the "159 '\u009f'" char, ArgumentException("The encoding is not supported.") is thrown.

Workaround:

Use PdfFormatProvider.

The exception is thrown with the message "Password is not correct" even when the user password is correct. This issue occurs for specific encryption algorithm parameters only.