This is reproducible with specific PDF files which use custom Encoding for the fonts of the field widgets. 

WORKAROUND: Change the font of VariableContentWidgets before editing the field value. You should additionally call RecalculateContent() method of these widgets if the value of their corresponding fields is not edited. The following method may be used for changing the font of all existing widgets in the document:

private static void FixEncodingIssues(RadFixedDocument document)
{
    foreach(Annotation annotation in document.Annotations)
    {
        VariableContentWidget widget = annotation as VariableContentWidget;

        if(widget != null)
        {
            widget.TextProperties.Font = FontsRepository.Helvetica;
        }
    }
}

Although Lab color space is currently unsupported, the provider should not throw exceptions that break the whole file import.

The issue is observed with tables that have a specific width (in inches or percents) but whose columns do not have width specified. MS Word renders such tables expanded to their full width. For tables with 100% width, they have to expand to the entire width of the page. The same behavior is expected in the PDF export.

As a common side effect, when specific text alignment (e.g. center or right) is applied to a paragraph within a table cell, and the table is with specified width, but the column is auto-sized (without set width), then the text alignment seems as not respected. Actually the problem is that the column table is shrunk to the text width.

Workaround: this may be used before exporting the RadFlowDocument instance to PDF:

foreach (Table table in document.EnumerateChildrenOfType<Table>())
{
    table.LayoutType = TableLayoutType.FixedWidth;
}


Workaround 2:

Set specific width to the auto-sized columns (to any of the cells in the columns):

cell.PreferredWidth = new Telerik.Windows.Documents.Flow.Model.Styles.TableWidthUnit(500);

Available in R1 2018 SP2 release version.

Formulas like =0.0001/10 or formulas that produce small values results in 0 instead of exponential numbers.


Available in LIB version: 2017.1.313

ArgumentException with clarification similar to  "'\u001f', hexadecimal value 0x1F, is an invalid character." is thrown when trying to export document containing characters which are not supported in XML document - such as some control characters like 0x00, 0x1F, 0x1B, etc. Such characters are described in the XML specification here: https://www.w3.org/TR/xml/#charsets.

Although the escaped strings are not supported (see  https://feedback.telerik.com/Project/184/Feedback/Details/190228 ), the library could prevent the exception and export the document successfully by skipping such characters.

Workaround: remove such characters before the export. Check the following StackOverflow answer for some ideas on code for replacing the characters: http://stackoverflow.com/a/14323524/259206

Fix available in R3 2018 SP1 release.

Workaround:

private static void WorkaroundFieldsIssue(RadFlowDocument flowdocument)
{
    foreach (FieldCharacter fieldCharacter in flowdocument.EnumerateChildrenOfType<FieldCharacter>().ToList())
    {
        // only for start
        if (fieldCharacter.FieldCharacterType == FieldCharacterType.Start)
        {
            if (fieldCharacter.FieldInfo.Separator != null && fieldCharacter.FieldInfo.Separator.Parent == null)
            {
                Paragraph parent = fieldCharacter.FieldInfo.End.Paragraph;
                int index = parent.Inlines.IndexOf(fieldCharacter.FieldInfo.End);

                fieldCharacter.FieldInfo.End.Paragraph.Inlines.Insert(index, fieldCharacter.FieldInfo.Separator);
            }
        }
    }
}

This may cause either big distance between some glyphs, or overlapping glyphs.

If we have a list (<ol>, <ul>) with list items (<li>) and there is a paragraph inside a list item(<p>), an empty additional paragraph is imported if the <p> element is right next to the <li> element (without a space). The indentation of child paragraphs in list item could be messed up as well. If there is a space between the HTML elements, the content is imported as expected.

Styled text in a list item <li> is imported as a different paragraph. The result is split of the text into multiple paragraphs which are not in a list.

The issue could be observed only when the text is written as a direct content of the <li> element. If it is in a <p> element the paragraph is imported correctly (it is not split). 

For example:

problematic html (the paragraph will be split) - <li>An appointment may create any provisions <strong>and</strong> in particular: </li>
non-problematic html (the paragraph will be imported as it should) - <li><p>An appointment may create any provisions <strong>and</strong> in particular: <p></li>

The issue is reproducible only with nested tables - tables positioned inside some other table cell. When using simple tables the text is always wrapped and rendered correctly. This may be used as a workaround for scenarios which allow replacing nested tables with simple ones.

The NotImplementedException is thrown while getting the color from unsupported color space (for example ICC). This exception occurs during the import of shading patterns with gradient stops using this color space or during the import of tiling pattern with underlying color space.

Available in R2 2018 Official Release Version.

An ArgumentException is thrown when importing HTML containing standard and non-standard pseudo classes or pseudo elements. The concreete scenario is the following: 
.myclass::-webkit-scrollbar or .myclass::-ms-expand

The message of the exception is similar to this: "Unexpected character found at position [X]: ".. scrollbar::>>-<<webkit-scrollbar"". 

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.

When importing an image whose Uri is not a full Uri, an exception is thrown.

When MergeField is present in the document, and this merge field is evaluated to an empty string - this, for example, happens when the property in the data source is set to null, empty string, or is missing at all - the result fragment remains in the result document. Instead, it should be removed.

Steps to reproduce: 
- Create document with merge field, the field should contain result fragment, and set data source which contains null or string.Empty value for the field:

            RadFlowDocument document = new RadFlowDocument();
            RadFlowDocumentEditor editor = new RadFlowDocumentEditor(document);

            editor.InsertField("MERGEFIELD FirstName ", "«FirstName»");

            List<Person> source = new List<Person>()
            {
                new Person() { FirstName = string.Empty }
            };

            RadFlowDocument mergedDocument = document.MailMerge(source);
Expected: The result document is empty.
Actual: The result document contains "«FirstName»" string.

Available in LIB Version 2017.3.1120.

When documents are exported to PDF, the creation date and modification date are not expected, or, when the time zone is with negative offset, the documents are invalid (detected by validation tools).

The data validation rule should have values for formula1 and formula2 elements, which define the start and end values for a range to validate between. When such values are missing, a NullReferenceException is thrown on import and the document cannot be imported.