sudo apt upgrade
Not upgrading:                 
  linux-base-amd64  linux-headers-amd64  linux-image-amd64

Summary:
  Upgrading: 0, Installing: 0, Removing: 0, Not Upgrading: 3

This is information is so useful, one can tell from output right away what the heck is happening.

I run Sid, and I see that frequently. It doesn't really tell you why the upgrade won't be done, but experience tells me that the dependencies haven't yet been made available. Dependencies can be convoluted and complicated. I just wait, and eventually the upgrade is available. It happens most frequently when a major upgrade of a major package is in process, for instance the entire Qt or Plasma environment. But it can happen with smaller packages. In the above instance, it appears that a new kernel is becoming available, but not all the dependencies are staged for installations, but it should be sorted in a few hours.

ran sudo apt ugrade last night, with just dnsmasq-bas being deferred, but nothing else available

This morning the result is shown below;

condobloke@brian-desktop:~$ sudo apt upgrade
[sudo] password for condobloke:
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Calculating upgrade... Done
The following upgrades have been deferred due to phasing:
dnsmasq-base
The following packages will be upgraded:
fonts-opensymbol libreoffice-base-core libreoffice-common libreoffice-core
libreoffice-style-colibre libreoffice-uiconfig-calc
libreoffice-uiconfig-common libreoffice-uiconfig-draw
libreoffice-uiconfig-impress libreoffice-uiconfig-writer libreoffice-writer
libuno-cppu3t64 libuno-cppuhelpergcc3-3t64 libuno-purpenvhelpergcc3-3t64
libuno-sal3t64 libuno-salhelpergcc3-3t64 python3-uno uno-libs-private ure
19 to upgrade, 0 to newly install, 0 to remove and 1 not to upgrade.
Need to get 86.3 MB of archives.
After this operation, 19.5 kB of additional disk space will be used.
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