我正在尝试将多个 .pdf 文件合并为一个。我收到一条错误消息，指出文件上有密码，这会阻止合并，但当我打开文件时没有密码请求，并且我设置了读取、写入以及作为文件执行的权限。
pdftk *.pdf cat output BankPackage-2023
WARNING: The creator of the input PDF:
OPEX Statement-4950 2022-10-20(1).pdf
has set an owner password (which is not required to handle this PDF).
You did not supply this password. Please respect any copyright.
有什么解决办法吗？