Fix concurrent HtmlParser corruption by removing static singleton (#956)

Copilot · Tyrrrz · web-flow · commit 228426f7d008 · 2026-05-28T19:20:42.000+03:00
Co-authored-by: copilot-swe-agent[bot] &lt;198982749+Copilot@users.noreply.github.com&gt;
Co-authored-by: Oleksii Holub &lt;1935960+Tyrrrz@users.noreply.github.com&gt;
diff --git a/YoutubeExplode/Utils/Html.cs b/YoutubeExplode/Utils/Html.cs
@@ -5,7 +5,10 @@ namespace YoutubeExplode.Utils;
 
 internal static class Html
 {
-    private static readonly HtmlParser HtmlParser = new();
-
-    public static IHtmlDocument Parse(string source) => HtmlParser.ParseDocument(source);
+    // A new HtmlParser instance must be created for each call to avoid thread safety issues
+    // when multiple YoutubeClient instances are used concurrently. HtmlParser is not thread-safe
+    // and sharing a single static instance causes corruption errors (InvalidOperationException)
+    // in AngleSharp's internal collections.
+    // https://github.com/Tyrrrz/YoutubeExplode/issues/955
+    public static IHtmlDocument Parse(string source) => new HtmlParser().ParseDocument(source);
 }

Original file line number	Diff line number	Diff line change
`@@ -5,7 +5,10 @@ namespace YoutubeExplode.Utils;`
`5`	`5`
`6`	`6`	`internal static class Html`
`7`	`7`	`{`
`8`		`- private static readonly HtmlParser HtmlParser = new();`
`9`		`-`
`10`		`- public static IHtmlDocument Parse(string source) => HtmlParser.ParseDocument(source);`
	`8`	`+ // A new HtmlParser instance must be created for each call to avoid thread safety issues`
	`9`	`+ // when multiple YoutubeClient instances are used concurrently. HtmlParser is not thread-safe`
	`10`	`+ // and sharing a single static instance causes corruption errors (InvalidOperationException)`
	`11`	`+ // in AngleSharp's internal collections.`
	`12`	`+ // https://github.com/Tyrrrz/YoutubeExplode/issues/955`
	`13`	`+ public static IHtmlDocument Parse(string source) => new HtmlParser().ParseDocument(source);`
`11`	`14`	`}`