Good Morning All,
Lately I have been getting the message "Not all updates can be installed". See attachment.
I don't want to upgrade, as keeping the LTS version is good with me. Is running the "partial upgrade" OK to do?
.
Thanks for all your help...
mt
If you’ve specified in software-properties-gtk to not allow upgrades to non-LTS systems, the partial upgrade process should not cause the core system to be upgraded past 16.04.
Try this to see if the problem will resolve itself;
sudo apt install -f
That does a variety of things, which normally resolves broken packages by removing them and installing other packages for upgraded versions of software as necessary.
If that doesn’t work out, then I suggest installing Synaptic from the Ubuntu MATE Welcome software boutique and peeking in there to see what else is broken and what can’t be upgraded. If a PPA has a sudden failure because of Launchpad not being accessible or the main servers are incapable of providing you necessary packages. you may need to find alternative software providers; take another look in software-properties-gtk to let it find the best servers for your area, and if you have to find alternative archives for the software you’re already using from PPAs.
Then try sudo apt install -f again to see if that resolves the issue. If not, and if it is because of some odd package you need from Debian or another distribution Ubuntu does not support outright, try to find an alternative on another Debian system’s online repository for the package(s) you need to resolve the issue of not being able to install all updates.
Thank You tiox, Here is what I got when I ran "sudo apt install -f" again...
Is this what I'm looking for?
Also how do I get to "software-properties-gtk " to see what is ticked?
Thanks again
mt
Anything I type in fixed-width font is a program. Reading your answer your own question. 
…Unless I typed it wrong and it’s “gtk-software-properties” but I am certain what I typed was correct. If you want to confirm in the terminal your software repos are active you can do sudo apt update (which would just update the available repos) but both software-properties-gtk and synaptic would report errors much the same.
One more thing you could try is sudo apt upgrade -s which would simulate an upgrade procedure. There you can see if you’ll encounter any errors related to existing software.
tiox,
The above is what you typed.
I’m not understanding what you wrote above in your reply.
Thanks
mt
If the above is set for LTS releases only, a partial upgrade should never under any circumstances upgrade you to a non-LTS release.
You can also reach that window from update-manager by clicking on Settings within that application.
A Manjaro look-alike, having repurposed all of the Manjaro XFCE theme settings for MATE. What’s missing; ClearLooksRE GTK window decoration, RAVEfinity Vibrancy, Cantarell Bold from Google, Knack (Hack-alike) from Nerd Fonts.
Hi @matetwo, it sure sounds like what I ran into a few weeks ago. Plus there seems to be some confusion mixing “update” and “upgrade” in a message.
What we experienced was a normal update snag. I didn’t even notice it said “upgrade”. Now it makes me think the lingo is not consistent.
Anyway, you’ll find several reports and a conclusion it’s a needless message here:
Hello,
OK… I set it for long term support versions.
Thank you for the help and having patience with me.
Getting old ain’t for sissies! 
mt
Seeing again on 18.04 LTS:
ThinkPad-T430:~$ update-manager
(software-properties-gtk:10545): Gtk-CRITICAL **: 09:07:43.316: gtk_box_gadget_distribute: assertion ‘size >= 0’ failed in GtkNotebook
(software-properties-gtk:10545): Gtk-CRITICAL **: 09:07:43.319: gtk_box_gadget_distribute: assertion ‘size >= 0’ failed in GtkNotebook
Traceback (most recent call last):
File “/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py”, line 368, in refresh_cache
self.cache = MyCache(None)
File “/usr/lib/python3/dist-packages/UpdateManager/Core/MyCache.py”, line 77, in init
assert(not self._dpkgJournalDirty())
AssertionError
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File “/usr/lib/python3/dist-packages/UpdateManager/Dialogs.py”, line 114, in
button.connect(“clicked”, lambda x: callback())
File “/usr/lib/python3/dist-packages/UpdateManager/Dialogs.py”, line 129, in on_settings_button_clicked
self.window_main.show_settings()
File “/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py”, line 216, in show_settings
self.start_available()
File “/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py”, line 238, in start_available
self.refresh_cache()
File “/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py”, line 401, in refresh_cache
self.update_list.update(self.cache, eventloop_callback=iterate)
File “/usr/lib/python3/dist-packages/UpdateManager/Core/UpdateList.py”, line 479, in update
self.distUpgradeWouldDelete = cache.saveDistUpgrade()
AttributeError: ‘NoneType’ object has no attribute ‘saveDistUpgrade’
Traceback (most recent call last):
File “/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py”, line 368, in refresh_cache
self.cache = MyCache(None)
File “/usr/lib/python3/dist-packages/UpdateManager/Core/MyCache.py”, line 77, in init
assert(not self._dpkgJournalDirty())
AssertionError
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File “/usr/lib/python3/dist-packages/UpdateManager/Dialogs.py”, line 114, in
button.connect(“clicked”, lambda x: callback())
File “/usr/lib/python3/dist-packages/UpdateManager/Dialogs.py”, line 339, in available
self.window_main.start_available(error_occurred=True)
File “/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py”, line 238, in start_available
self.refresh_cache()
File “/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py”, line 401, in refresh_cache
self.update_list.update(self.cache, eventloop_callback=iterate)
File “/usr/lib/python3/dist-packages/UpdateManager/Core/UpdateList.py”, line 479, in update
self.distUpgradeWouldDelete = cache.saveDistUpgrade()
AttributeError: ‘NoneType’ object has no attribute ‘saveDistUpgrade’
Going to do reinstall ‘sudo apt-get install --reinstall update-manager synaptic’
