The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.
ublic void ProcessFolderForHtml(string sourcePath,…...AppendLine("<table><tr>"); html.AppendLine($"<td><img...html.AppendLine("</td></tr></table><hr/>"); // Tree root (OST file...