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,…...FromFile(sourcePath)) { var html = new StringBuilder(); html.AppendLine("<...AppendLine("<!DOCTYPE html><html lang='en'><head><meta charset='UTF-8'>");...