python2-twisted could not satisfy dependency

ykonstant · 2021-03-30 22:02:17

Dear all,

I am trying to do an update today with

sudo pacman -Syu

, and I get the following error message:

    :: Starting full system upgrade...
    :: Replace python2-twisted with extra/python-twisted? [Y/n] Y
    resolving dependencies...
    looking for conflicting packages...
    error: failed to prepare transaction (could not satisfy dependencies)
    :: removing python2-twisted breaks dependency 'python2-twisted' required by python2-incremental

I do not use python myself, and have not messed with any settings, so I do not know how this confict arises or how to resolve it. Can anyone help with this?

Last edited by ykonstant (2021-03-30 22:03:00)

WorMzy · 2021-03-30 22:25:56

There has been a renewed drive to purge the old python2 packages from the repos, and python2-twisted and python2-incremental have been recently dropped due to this (although apparently python-twisted 'replaces' python2-twisted).

So, on your system, what requires python2-incremental?

pacman -Qi python2-incremental | grep "Required By"

Is it another python2 package? If so what requires that? Etc.

A quicker way to follow the chain down is to cascade remove the package. e.g.

# pacman -Rsc python2-incremental

However, note the warning in pacman's manpage:

       -c, --cascade
           Remove all target packages, as well as all packages that depend on one or more target packages. This
           operation is recursive and must be used with care, since it can remove many potentially needed packages.

See what pacman tells you will be removed as a consequence of removing the package and the packages that depend on it. Decide whether this is something you are willing to accept.

ykonstant · 2021-03-30 22:41:44

WorMzy wrote:

There has been a renewed drive to purge the old python2 packages from the repos, and python2-twisted and python2-incremental have been recently dropped due to this (although apparently python-twisted 'replaces' python2-twisted).
So, on your system, what requires python2-incremental?
pacman -Qi python2-incremental | grep "Required By"
Is it another python2 package? If so what requires that? Etc.
A quicker way to follow the chain down is to cascade remove the package. e.g.
# pacman -Rsc python2-incremental
However, note the warning in pacman's manpage:
       -c, --cascade
           Remove all target packages, as well as all packages that depend on one or more target packages. This
           operation is recursive and must be used with care, since it can remove many potentially needed packages.
See what pacman tells you will be removed as a consequence of removing the package and the packages that depend on it. Decide whether this is something you are willing to accept.

Running the pacman command you suggested, I get:

Required By     : python2-twisted

Then, running the code on python2-twisted, I get:

Required By     : python2-incremental

I am confused They seem to require each other.

Last edited by ykonstant (2021-03-30 22:42:19)

gugah · 2021-03-30 22:42:27

I'm having the same issue and this is what I get when checking the packages that require python2-twisted and python2-incremental:

$ pacman -Qi python2-incremental | grep "Required By"
Required By     : python2-twisted

$ pacman -Qi python2-twisted | grep "Required By"
Required By     : python2-incremental

Looks like I can get rid of both, right? I wonder how I got those packages in the first place

edit: ykonstant posted right before I did, sorry for the double-post

Last edited by gugah (2021-03-30 22:45:56)

loqs · 2021-03-30 22:49:10

Have a look at the dependencies of https://archlinux.org/packages/extra/an … cremental/ which are the same as the python2 version.
Most likely something depending on python2-twisted pulled in python2-incremental and the package requiring python2-twisted has been updated to python-twisted or been dropped.

eschwartz · 2021-03-30 22:50:32

https://bugs.archlinux.org/task/70036

The python3 version does "replace" the python2 version because it provides a bunch of programs in /usr/bin

According to my IRC logs we finally dropped the package after removing sslstrip from the repos (the last thing depending on it).

The ongoing purge of python2 happens in spurts, but mainly whenever we find a package has been ported to python3 in the next version -- or, contrarily, the maintainer decides it is no longer worth keeping around as it will never be fixed and it isn't worth waiting on.

WorMzy · 2021-03-30 22:52:08

Looks like I can get rid of both, right?

Yes, if they only require each other, but you don't otherwise need either one, remove both, then complete the upgrade. They were probably installed as dependencies of something else which you have since removed (or has dropped the dep).

Scimmia · 2021-03-30 22:56:42

eschwartz wrote:

The python3 version does "replace" the python2 version because it provides a bunch of programs in /usr/bin

I'm not sure it should, though. This essentially blacklists python2-twisted from being installed from the AUR or elsewhere. It also doesn't really replace the python2 version, as it's not the same thing. replaces is more for package renames.

eschwartz · 2021-03-30 23:04:00

It shouldn't, as a matter of philosophy, but it does, as a matter of historical reality...

+# Adding replaces here because python2-twisted is no longer supported, all the command line tools
+# are now provided by the python3 variant.
+replaces=('python2-twisted')

The correct solution, really, is to first add a *versioned* replaces so it only replaces "python2-twisted<=20.3.0-3", and after that, ponder whether to remove the replaces altogether as people likely did not install it for the tools per se.

I feel like I've recommended the versioned replaces at least, but I can't actually find where I've done so.

EDIT: I've just definitely recommended it right now to Felix.

Last edited by eschwartz (2021-03-30 23:07:41)

Arch Linux

#1 2021-03-30 22:02:17

python2-twisted could not satisfy dependency

#2 2021-03-30 22:25:56

Re: python2-twisted could not satisfy dependency

#3 2021-03-30 22:41:44

Re: python2-twisted could not satisfy dependency

#4 2021-03-30 22:42:27

Re: python2-twisted could not satisfy dependency

#5 2021-03-30 22:49:10

Re: python2-twisted could not satisfy dependency

#6 2021-03-30 22:50:32

Re: python2-twisted could not satisfy dependency

#7 2021-03-30 22:52:08

Re: python2-twisted could not satisfy dependency

#8 2021-03-30 22:56:42

Re: python2-twisted could not satisfy dependency

#9 2021-03-30 23:04:00

Re: python2-twisted could not satisfy dependency

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