Cura install not possible on Mint 18.1 KDE Edition

[Ndimensional]

I tried to install a 3D slicing software (Cura 2.4.0) as PPA on my Linux Mint installation. But I could not install due to an error message:
-----------------------------------------------------------------------------------------
what I did:
apt add-repository ppa:thopiekar/cura
apt update
and finally (LANG=C for english output):
LANG=C apt install cura
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
cura : Depends: python3-uranium but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
-----------------------------------------------------------------------------------------
Some root cause analysis later I found:
- it can be installed seamlessly on a Cinnamon edition
- it can NOT be installed on a KDE edition

I tested it on clean installations of Linux Mint 18.1 - fresh downloaded - of the Cinnamon and KDE edition, both 64 Bit

So it looks like the Linux Mint KDE edition has some problems or differences to Cinnamon in context of Python3-uranium .....

[eojl]

The Cura PPA should have the package python3-uranium, so I would try installing it again.

[Ndimensional]

Well, I did, believe me. Also I checked with the package maintainer himself and someone else with some more knowledge than me - about Mint,packages and dependencies.
The error message is the same whenever it is installed on a KDE edition - in Cinnamon it runs smoothlessly. I will also try now MATE and Xfce - but as it looks itś the backport part of KDE..

It is a problem in the Mint KDE Edition with the QT packages..... how else could you explain why it runs on Cinnamon and not on KDE? The only ppa installed in Mint KDE in the beginning - and that is a difference to Cinnamon - is the kubuntu-backport one - and there the problem is located....

[richyrich]

This is probably a list of the files that are in conflict :

https://github.com/Ultimaker/Uranium/wi ... -on-Ubuntu

[Ndimensional]

Dont think so - Python 3.5.6 IS installed - and when I understand the Cura post correctly you "only" need 3.4.x
And again - no problem when installing on Linux Mint 18.1 Cinnamon - the Cura post refers generally to Ubuntu, no reference to KDE.

[richyrich]

I was thinking that the problem was with PyQt 5.4 . . oops sorry.

[Ndimensional]

Well somehow this seems to be the case - but via the "kubuntu-ppa/backports". Python is relating to some missing or wrong Qt packages --> see initial problem chase under:
https://ultimaker.com/en/community/3962 ... -installed

So first cura install complains about missing dependency to Python3-uranium. When trying to install exactly this package the following error message is shown - complaining about broken packages in a clean installed Mint 18.1 KDE:
-----------------------------------------------------

apt install python3-uranium

Reading package lists... Done

Building dependency tree

Reading state information... Done

Some packages could not be installed. This may mean that you have

requested an impossible situation or if you are using the unstable

distribution that some required packages have not yet been created

or been moved out of Incoming.

The following information may help to resolve the situation:

The following packages have unmet dependencies:

python3-uranium : Depends: python3-pyqt5 but it is not going to be installed

Depends: python3-pyqt5.qtopengl but it is not going to be installed

Depends: python3-pyqt5.qtquick but it is not going to be installed

Depends: python3-pyqt5.qtsvg but it is not going to be installed

E: Unable to correct problems, you have held broken packages.

xxxxxx@Tower-Mint ~ $ python -V

Python 2.7.12

xxxxxx@Tower-Mint ~ $ python3 -V

Python 3.5.2

[richyrich]

Yup, I see the pyqt5 errors too. I still think that pyqt5 (5.4 as per the link) cannot be there or it is a wrong/different version, else everything else would work.

[Ndimensional]

ok, so I just finished checking the different Mint versions. I created a clean system for each version and installed only cura 2.4.0 from the PPA.
Results:
Cinnamon - success
Mate - success
Xfce - success
KDE - fail

So it is IMHO not a PPA problem but a KDE one.

[acheronuk]

PyQt5 packages depend on the ABI of the Qt version they were build against. So in that ppa they are built against the stock Xenial Qt 5.5 and packages so depend on qtbase-abi-5-5-1 and qtdeclarative-abi-5-5-0 etc.

Mint 18.1 KDE packages and PyQt5 REQUIRE and are built with and provide Qt 5.6.1, so ABI 5-6-1, and a ppa with packages built against and depending on the 5.5 ABI will not be installable.

Efforts have been made to ensure as much compatibility with the new ABI in archive and official ppa repositories, with rebuilds against the bumped ABI if needed.

However, this is an unsupported 3rd party ppa not built with installing on Mint 18.1 KDE in mind. To support that it would at least need a rebuild of the affected packages in a separate ppa with the kubuntu backports as a dependency or a compatible build of Qt included.

[Ndimensional]

Well, if this is the only package which has this problem I would stop the search and analysis here - at least there is an Appimage which works instead of the PPA. I was not sure if this could be a problem for others as well....
So thanky ou all for your help/ input!

[stampedeboss]

Is the only solution to convert back to KUbuntu? I've been a user of Mint since 8 and hate to leave.