为什么更新管理器显示无法检查的未经检查的更新？

如果您从命令行运行，几乎总是可以看到更多信息。
单击对话框中的“稍后提醒我”，然后尝试下面的操作

更多解释： https://ubuntu.com/server/docs/about-apt-upgrade-and-phased-updates

下面您可以看到在 24.04 执行此操作时的当前状态（在撰写本文时）。

请注意
The following upgrades have been deferred due to phasing:
The following packages have been kept back:

... 下面列出的项目phasing是为了减少流量，不是每个人都能同时获得它。
kept back一些东西可能是可安装的，但通常会替换或删除一个或多个包，如果你安装这些，你也可能会遇到故障和错误 - 尚未被检测到。
（使用sudo apt-get --with-new-pkgs upgrade来安装它们）

$ sudo apt-get upgrade  
The following upgrades have been deferred due to phasing:
  file-roller gnome-text-editor icu-devtools language-pack-en
  language-pack-gnome-en-base libicu-dev libicu74 libicu74:i386 liblzma-dev
  liblzma5 liblzma5:i386 python-apt-common python3-apt xz-utils
The following packages have been kept back:
  language-pack-en-base language-pack-gnome-en
The following packages will be upgraded:
  language-pack-gnome-sv language-pack-gnome-sv-base libpython3-dev
  libpython3-stdlib python3 python3-dev python3-minimal
7 upgraded, 0 newly installed, 0 to remove and 16 not upgraded.
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