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,…..."data:image/png;base64," + Convert.ToBase64String(File.ReadAllBytes(logoPath));..."data:image/gif;base64," + Convert.ToBase64String(File.ReadAllBytes(folderIconPath));...