Catch WebKit load failures on account login. Wrap the code path that opens NativeWebDialog / WebView for Audible login in a try/catch for DllNotFoundException (and related load failures). On failure, show a short dialog: install WebKit2GTK and do not crash the app.

Source/LibationAvalonia/Dialogs/Login/AvaloniaLoginChoiceEager.cs

@@ -100,12 +100,44 @@ public class AvaloniaLoginChoiceEager : ILoginChoiceEager
 			dialog.Source = new Uri(shoiceIn.LoginUrl);
 		};
 
-		if (!Configuration.IsLinux && App.MainWindow is TopLevel topLevel)
-			dialog.Show(topLevel);
-		else
-			dialog.Show();
+		// NativeWebDialog can fault on a posted dispatcher job (e.g. missing libwebkit2gtk on Linux), which bypasses a try/catch around Show().
+		void onUnhandledException(object? sender, DispatcherUnhandledExceptionEventArgs e)
+		{
+			if (!WebView2LoginErrorMessage.IsWebView2SignInInfrastructureFailure(e.Exception))
+				return;
+			e.Handled = true;
+			try
+			{
+				dialog.Close();
+			}
+			catch
+			{
+				/* ignore */
+			}
+			tcs.TrySetException(e.Exception);
+		}
 
-		return await tcs.Task;
+		Dispatcher.UIThread.UnhandledException += onUnhandledException;
+		try
+		{
+			try
+			{
+				if (!Configuration.IsLinux && App.MainWindow is TopLevel topLevel)
+					dialog.Show(topLevel);
+				else
+					dialog.Show();
+			}
+			catch (Exception ex) when (WebView2LoginErrorMessage.IsWebView2SignInInfrastructureFailure(ex))
+			{
+				tcs.TrySetException(ex);
+			}
+
+			return await tcs.Task;
+		}
+		finally
+		{
+			Dispatcher.UIThread.UnhandledException -= onUnhandledException;
+		}
 
 		void Dialog_EnvironmentRequested(object? sender, WebViewEnvironmentRequestedEventArgs e)
 		{

Source/LibationUiBase/WebView2LoginErrorMessage.cs

@@ -11,21 +11,56 @@ public static class WebView2LoginErrorMessage
 {
 	public const string Caption = "Sign-in browser could not start";
 
-	public static string ExplainerBody =>
-		"Libation could not start the in-app sign-in browser. On Windows this uses Microsoft WebView2. "
-		+ "This is a local sign-in or system setup issue — not a failure of the library scan itself.\r\n\r\n"
-		+ "Things to try:\r\n"
-		+ "• On Windows: install or repair the Microsoft Edge WebView2 Runtime from https://developer.microsoft.com/microsoft-edge/webview2/\r\n"
-		+ "• In Libation Settings, try turning off the option to use the embedded browser and use external browser sign-in instead.\r\n"
-		+ "• Check that security software is not blocking Libation or the embedded browser.\r\n"
-		+ "• Ensure your account can write to local app data folders (permissions).\r\n"
-		+ "• If you run as Administrator, try running Libation as a normal user (or the reverse).\r\n\r\n"
-		+ "After sign-in works, use Import again to scan your library.";
+	public static string ExplainerBody
+	{
+		get
+		{
+			const string localIssue =
+				"This is a local sign-in or system setup issue — not a failure of the library scan itself.\r\n\r\n";
+			const string thingsToTry = "Things to try:\r\n";
+			const string settingsBullet =
+				"• In Libation Settings, try turning off the option to use the embedded browser and use external browser sign-in instead.\r\n";
+			const string securityBullet =
+				"• Check that security software is not blocking Libation or the embedded browser.\r\n";
+			const string permissionsBullet =
+				"• Ensure your account can write to local app data folders (permissions).\r\n";
+			const string adminBullet =
+				"• If you run as Administrator, try running Libation as a normal user (or the reverse).\r\n\r\n";
+			const string footer = "After sign-in works, use Import again to scan your library.";
+
+			if (OperatingSystem.IsLinux())
+			{
+				return "Libation could not start the in-app sign-in browser. On Linux this uses WebKit2GTK (native WebKit). "
+					+ localIssue
+					+ thingsToTry
+					+ "• Install WebKit2GTK for your distro (e.g. on Arch: webkit2gtk or webkit2gtk-4.1).\r\n"
+					+ settingsBullet
+					+ securityBullet
+					+ permissionsBullet
+					+ adminBullet
+					+ footer;
+			}
+
+			return "Libation could not start the in-app sign-in browser. On Windows this uses Microsoft WebView2. "
+				+ localIssue
+				+ thingsToTry
+				+ "• On Windows: install or repair the Microsoft Edge WebView2 Runtime from https://developer.microsoft.com/microsoft-edge/webview2/\r\n"
+				+ settingsBullet
+				+ securityBullet
+				+ permissionsBullet
+				+ adminBullet
+				+ footer;
+		}
+	}
 
 	public static bool IsWebView2SignInInfrastructureFailure(Exception ex)
 	{
 		for (var e = ex; e is not null; e = e.InnerException)
 		{
+			// Gtk / WebView2: missing native WebKit or WebView2 runtime often surfaces as DllNotFoundException (sometimes without a useful stack).
+			if (e is DllNotFoundException dll && IsEmbeddedWebViewNativeDllFailure(dll))
+				return true;
+
 			if (!StackMentionsEmbeddedSignInBrowser(e))
 				continue;
 
@@ -40,6 +75,18 @@ public static class WebView2LoginErrorMessage
 		return false;
 	}
 
+	/// <summary>
+	/// Gtk WebView (e.g. Avalonia NativeWebDialog on Linux) requires WebKit2GTK; minimal installs omit <c>libwebkit2gtk</c>.
+	/// </summary>
+	private static bool IsEmbeddedWebViewNativeDllFailure(DllNotFoundException e)
+	{
+		if (e.Message.Contains("libwebkit2gtk", StringComparison.OrdinalIgnoreCase)
+			|| e.Message.Contains("webkit2gtk", StringComparison.OrdinalIgnoreCase))
+			return true;
+
+		return StackMentionsEmbeddedSignInBrowser(e);
+	}
+
 	public static bool TryFindInTree(Exception ex, out Exception? match)
 	{
 		Exception? found = null;
@@ -70,6 +117,8 @@ public static class WebView2LoginErrorMessage
 		return stack is not null
 			&& (stack.Contains("WebView2", StringComparison.Ordinal)
 				|| stack.Contains("CoreWebView2", StringComparison.Ordinal)
-				|| stack.Contains("NativeWebDialog", StringComparison.Ordinal));
+				|| stack.Contains("NativeWebDialog", StringComparison.Ordinal)
+				|| stack.Contains("GtkWebView", StringComparison.Ordinal)
+				|| stack.Contains("WebViewControlAvalonia", StringComparison.Ordinal));
 	}
 }