Migrate from v5

v6 is a rewrite of the conversion engine, but the public surface stays largely source-compatible: the old Config members remain as [Obsolete] shims that forward to the new grouped members. Existing code keeps compiling (with deprecation warnings guiding you to the new API).

Engine

• HTML is now parsed with AngleSharp (HTML5-compliant) instead of HtmlAgilityPack, and rendered through per-flavor writers over an intermediate Markdown DOM.
• Custom converters written against the v5 HtmlNode/IConverter model no longer apply. Use the v6 reader/writer model instead - IMdReader + [MarkdownReader], or the Parse/Render DOM.

Config reorganization

Options are now grouped. The former flat properties are obsolete aliases:

v5 (obsolete)	v6
SmartHrefHandling	Links.SmartHref
WhitelistUriSchemes	Links.WhitelistedSchemes
TableWithoutHeaderRowHandling	Tables.WithoutHeaderRow
TableHeaderColumnSpanHandling	Tables.HeaderColumnSpans
UnknownTags	Tags.Unknown
UnknownTagsReplacer	Tags.Replacer
TagAliases	Tags.Aliases
PassThroughTags	Tags.PassThrough
Base64Images	Images.Base64Handling
Base64ImageSaveDirectory	Images.Base64Directory
Base64ImageFileNameGenerator	Images.Base64FileName
LazyImageSrcFallback	Images.LazySrcFallback
LazyImageSourceAttributes	Images.LazySourceAttributes
CleanupUnnecessarySpaces	Formatting.CleanupSpaces
SuppressDivNewlines	Formatting.SuppressDivNewlines
RemoveComments	Formatting.RemoveComments
ConvertPreContentAsHtml	Formatting.PreAsHtml
EscapeMarkdownLineStarts	Formatting.EscapeLineStarts
OutputLineEnding	Formatting.OutputLineEnding
ListBulletChar	Formatting.ListBulletChar
DefaultCodeBlockLanguage	Formatting.DefaultCodeBlockLanguage

Flavor model

• Flavor (the MarkdownFlavor enum) is now the single, canonical flavor selector.
• SlackFlavored, TelegramMarkdownV2, and CommonMark are obsolete aliases of Flavor.
• GithubFlavored stays distinct - it produces clean GFM markdown on the default writer and is not the same as Flavor = MarkdownFlavor.GitHub (the CommonMark-based GitHub writer, which preserves raw HTML). See GitHub.

Target frameworks

v6 targets netstandard2.0;net8.0;net9.0;net10.0. The netstandard2.0 target restores support for .NET Framework 4.6.1+, .NET Core 2.0+, Mono, and Unity. The HtmlAgilityPack dependency is removed (replaced by AngleSharp).