Copy this method to your Global Class in AX. public static void appendTextFile(str fromFilePath,str toFilePath) { FileIOPermission fromPerm; FileIOPermission toPerm; System.String text; System.IO.FileStream fs; System.IO.StreamReader reader; ; if(System.IO.File::Exists(fromFilePath) && System.IO.File::Exists(toFilePath)) { // Read text from file reader = new System.IO.StreamReader(fromFilePath); text = reader.ReadToEnd(); reader.Close(); // Append System.IO.File::AppendAllText(toFilePath,text); } else { throw error("Invalid path or file does not exist"); } }