Linux 安装程序包时出错：已安装的grub-efi-amd64程序包安装后脚本子流程返回错误退出状态255

我最近开始在戴尔XPS笔记本电脑上使用KDE Neon作为主要操作系统。 我通常使用Discover安装系统更新。然而，在安装任何系统更新时，我很晚才收到此错误消息

Fatal error: Error while installing package: installed grub-efi-amd64 package post-installation script subprocess returned error exit status 255

我在网上四处寻找帮助，并尝试了一些建议，如apt安装——重新安装grub-efi-amd64和dpkg——配置-a，我在终端上看到下面的消息。我不记得中断过机器上的任何更新。此系统是一个UEFI系统，EFI分区位于/boot/EFI上

Setting up grub-efi-amd64 (2.04-1ubuntu26.2) ...
od: /sys/firmware/efi/efivars/SecureBoot-8be4df61-93ca-11d2-aa0d-00e098032b8c: Operation not permitted
/usr/share/grub/grub-check-signatures: 22: [: Illegal number: 
dpkg: error processing package grub-efi-amd64 (--configure):
 installed grub-efi-amd64 package post-installation script subprocess returned error exit status 255
dpkg: dependency problems prevent configuration of grub-efi-amd64-signed:
 grub-efi-amd64-signed depends on grub-efi-amd64 | grub-pc; however:
  Package grub-efi-amd64 is not configured yet.
  Package grub-pc is not installed.

dpkg: error processing package grub-efi-amd64-signed (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of shim-signed:
 shim-signed depends on grub-efi-amd64-signed | grub-efi-arm64-signed; however:
  Package grub-efi-amd64-signed is not configured yet.
  Package grub-efi-arm64-signed is not installed.

dpkg: error processing package shim-signed (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 grub-efi-amd64
 grub-efi-amd64-signed
 shim-signed

我检查了文件/usr/share/grub/grub检查签名，这是第22行的内容

    21          if ! [ -f $efivars/$secureboot_var ] \
    22                  || [ "$(od -An -t u1 $efivars/$secureboot_var | awk '{ print $NF }')" -ne 1 ]
    23          then
    24                  return 1
    25          fi

我不知道是什么在颠覆我的系统。非常感谢您的帮助（如果可能的话，希望避免重新安装操作系统）