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,…...ellar Converter OLM TO PST Online</div>"); html.AppendLine($"<div...open it in a browser or an online Base‑64 decoder. If the decoder...