Multiple calls to Markdown.ToHtml with same pipeline parameter throws an exception #6

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claunia · 2026-01-29T14:19:03Z

claunia commented

2026-01-29 14:19:03 +00:00

Originally created by @pekkah on GitHub (May 29, 2016).

When calling Render method of following class more than once Markdown.ToHtml throws an exception (at the bottom). It seems to be related to the _pipeline parameter. If I remove it from the parameters multiple calls work as expected.

Class:

 public class MarkdigRenderer : IMarkdownRenderer
    {
        private readonly MarkdownPipeline _pipeline;

        public MarkdigRenderer()
        {
            _pipeline = new MarkdownPipeline().UseAllExtensions();
            _pipeline.DebugLog = new StringWriter();
        }

        public string Render(string markdown)
        {
            var html =  Markdown.ToHtml(markdown, _pipeline);

            return html;
        }
    }

Exception

System.InvalidOperationException: The character `:` is already used by another emphasis descriptor
   at Markdig.Parsers.Inlines.EmphasisInlineParser.Initialize(InlineProcessor processor)
   at Markdig.Parsers.ParserList`2.Initialize(TState initState)
   at Markdig.Parsers.InlineParserList.Initialize(InlineProcessor initState)
   at Markdig.Parsers.InlineProcessor..ctor(StringBuilderCache stringBuilders, MarkdownDocument document, InlineParserList parsers)
   at Markdig.Parsers.MarkdownParser..ctor(TextReader reader, MarkdownPipeline pipeline)
   at Markdig.Parsers.MarkdownParser.Parse(TextReader reader, MarkdownPipeline pipeline)
   at Markdig.Markdown.ToHtml(TextReader reader, TextWriter writer, MarkdownPipeline pipeline)
   at Markdig.Markdown.ToHtml(TextReader reader, MarkdownPipeline pipeline)
   at Markdig.Markdown.ToHtml(String markdown, MarkdownPipeline pipeline)

Originally created by @pekkah on GitHub (May 29, 2016). When calling Render method of following class more than once `Markdown.ToHtml` throws an exception (at the bottom). It seems to be related to the `_pipeline` parameter. If I remove it from the parameters multiple calls work as expected. Class: ``` public class MarkdigRenderer : IMarkdownRenderer { private readonly MarkdownPipeline _pipeline; public MarkdigRenderer() { _pipeline = new MarkdownPipeline().UseAllExtensions(); _pipeline.DebugLog = new StringWriter(); } public string Render(string markdown) { var html = Markdown.ToHtml(markdown, _pipeline); return html; } } ``` Exception ``` System.InvalidOperationException: The character `:` is already used by another emphasis descriptor at Markdig.Parsers.Inlines.EmphasisInlineParser.Initialize(InlineProcessor processor) at Markdig.Parsers.ParserList`2.Initialize(TState initState) at Markdig.Parsers.InlineParserList.Initialize(InlineProcessor initState) at Markdig.Parsers.InlineProcessor..ctor(StringBuilderCache stringBuilders, MarkdownDocument document, InlineParserList parsers) at Markdig.Parsers.MarkdownParser..ctor(TextReader reader, MarkdownPipeline pipeline) at Markdig.Parsers.MarkdownParser.Parse(TextReader reader, MarkdownPipeline pipeline) at Markdig.Markdown.ToHtml(TextReader reader, TextWriter writer, MarkdownPipeline pipeline) at Markdig.Markdown.ToHtml(TextReader reader, MarkdownPipeline pipeline) at Markdig.Markdown.ToHtml(String markdown, MarkdownPipeline pipeline) ```

claunia added the bug label 2026-01-29 14:19:04 +00:00

claunia closed this issue

2026-01-29 14:19:08 +00:00

claunia commented

2026-01-29 14:19:11 +00:00

@xoofx commented on GitHub (May 30, 2016):

Thanks this should be fixed by commit 09beb2f (nuget version: 0.1.1)

@xoofx commented on GitHub (May 30, 2016): Thanks this should be fixed by commit 09beb2f (nuget version: 0.1.1)

claunia commented

2026-01-29 14:19:16 +00:00

@xoofx commented on GitHub (May 31, 2016):

Note that latest version (0.2.0+) is introducing a MarkdownPipelineBuilder instead to disallow mutable pipeline (related to issue #5).

Replace

var pipeline = new MarkdownPipeline().UseAllExtensions()

by:

var pipeline = new MarkdownPipelineBuilder().UseAllExtensions().Build();

@xoofx commented on GitHub (May 31, 2016): Note that latest version (0.2.0+) is introducing a `MarkdownPipelineBuilder` instead to disallow mutable pipeline (related to issue #5). Replace ``` var pipeline = new MarkdownPipeline().UseAllExtensions() ``` by: ``` var pipeline = new MarkdownPipelineBuilder().UseAllExtensions().Build(); ```

claunia referenced this issue

2026-01-29 14:44:31 +00:00

Crashing on iOS and Android after usage over 1000 times #741

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Reference: starred/markdig#6