我正在尝试运行 sudo apt upgrade 但出现以下错误：
Setting up shim-signed (1.34.9+13-0ubuntu2) ...
Installing for x86_64-efi platform.
EFI variables are not supported on this system.
EFI variables are not supported on this system.
grub-install: error: efibootmgr failed to register the boot entry: No such file or directory.
dpkg: error processing package shim-signed (--configure):
installed shim-signed package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
shim-signed
E: Sub-process /usr/bin/dpkg returned an error code (1)
我尝试重新安装 grub 但似乎没有任何作用，有人能给我指明正确的方向吗？