Package dependencies cannot be resolved

[teo1978]

Every once in a while, the Software Updater window pops up as expected letting me know that there are updates ready to download and install.

Lately I have been clicking on "remind me later" every time for several weeks and only today I have finally clicked on "install now" (or "update now" or whatever the button is called).

I don't know whether that's relevant: had I installed the updates before rather than delaying them for many days, would I have got the same error? I don't know. Either way, that shouldn't be a problem.

Now that I did, I got this error (see attached screenshot).

First of all, if I get a "dependencies cannot be resolved" error, whatever it means, there's a bug somewhere. You are the package manager, it's your job to resolve and install dependencies. I have done nothing to prevent you from doing so, so if you can't resolve and install all the needed dependencies, something is wrong somewhere.

Secondly, the error message doesn't tell me anything that I can act upon. What am I supposed to do? It's great that you give me information about the error but it's not enough if you don't give me something I can act upon. Tell me what I shoul do.

Thirdly, let's have a look at the specific errors that are listed in this instance.

>>> "libxml2: Depends: libicus65 (>=2.15) but 2.23-Oubuntu11 is to be installed"

First of all, this is unclear af. "IS TO BE" is the part that confuses me. But I assume it means "is ABOUT" or "is GOING" to be installed. So, ok.

So, a version greater than or equal to 2.15 of that package is required, "BUT" version 2.23-something is going to be installed... "instead", I guess.
Well, it seems to me like 2.23 **IS** greater than or equal to 2.15, so what the fuck are you complaining about in the first place.

And then if it were true that that version is not compatible with your requirements, then why is that? What is preventing you from installing the version you need? I'm not saying there isn't a good reason, I'm saying the whole point of the error message is to tell me what the fuck the problem is and you are not giving me that information.

But the bigger point here is that what I'm reading seems to say that your problem is that you need a version of a package that is >=2.15 and 2.23 doesn't satisfy that requirement, which is absolute nonsense.

And every single error in the list is like that:

   "X: depends: Y (>=N) but M is to be installed"

with M > N.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: update-manager 1:16.04.17
ProcVersionSignature: Ubuntu 4.4.0-173.203-generic 4.4.208
Uname: Linux 4.4.0-173-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia
ApportVersion: 2.20.1-0ubuntu2.21
Architecture: amd64
CurrentDesktop: Unity
Date: Sun May 3 15:53:56 2020
DpkgHistoryLog.txt:

DpkgTerminalLog.txt:

InstallationDate: Installed on 2013-10-11 (2395 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
PackageArchitecture: all
SourcePackage: update-manager
UpgradeStatus: No upgrade log present (probably fresh install)

[teo1978 (teo8976)]

And then I simply clicked "Retry", it went through another round of installing stuff, and it finished without errors.

So if simply "retrying" could fix whatever error you were complaning about, why couldn't you get it right the first time?

[Sebastien Bacher (seb128)]

Thank you for your bug report, looks like you confused your system by enabling some external archives, you have versions with +deb.suri.org in the name. Could you try what's the output on a command line of?
$ sudo apt -f install

[teo1978 (teo8976)]

$ sudo apt -f install
[sudo] password for teo:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  bogofilter bogofilter-bdb bogofilter-common evolution-common fonts-horai-umefont fonts-unfonts-core geoip-database-extra gtk2-engines-pixbuf
  libchamplain-gtk-0.12-0 libcryptui0a libcurl3-gnutls:i386 libevolution libgif7:i386 libicu63 libjs-openlayers libllvm4.0 libllvm4.0:i386 libllvm5.0
  libllvm5.0:i386 libmuparser2v5 libp11-kit-gnome-keyring:i386 libpst4 libqmi-glib1 libqpdf17 librecad-data librtmp1:i386 libsodium18 libvpx3:i386
  libwireshark8 libwiretap6 libwscodecs1 libwsutil7 libytnef0 libzip5 linux-headers-4.4.0-171 linux-headers-4.4.0-171-generic linux-image-4.4.0-171-generic
  linux-modules-4.4.0-171-generic linux-modules-extra-4.4.0-171-generic ocl-icd-libopencl1:i386 odbcinst odbcinst1debian2 openshot-doc p7zip python-mlt
  python-pygoocanvas seahorse-daemon snapd-login-service unixodbc wine-gecko2.21 wine-gecko2.21:i386 wine-mono0.0.8 winetricks
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 13 not upgraded.

Note that this is after the error went away as per comment 2