How to identify and resolve a dependency conflict¶

Example error:

  1. Could not find a version that matches Django<1.10,<1.10.999,<1.11,<1.12,<1.9.999,<2,
  2. <2.0,==1.9.13,>1.3,>=1.11,>=1.3,>=1.4,>=1.4.10,>=1.4.2,>=1.5,>=1.6,>=1.7,>=1.8

Packages in your project specified conflicting dependencies. In the example above, there is noversion of Django that matches the constraint >=1.11 and also several of the others.

This can happen when you have specified versions of packages that themselves require conflictingversions of some other package. Often, especially in a project that used to work, it’s caused by anunpinned requirement, that then demands an unexpected dependency.

We can see from the error that Django>=1.11 is the problem, so we can search through the log tofind what added it:

  1. adding Django>=1.11
  2.   from django-phonenumber-field==2.0.0

A search for adding django-phonenumber-field reveals:

  1. adding django-phonenumber-field>=0.7.2
  2.   from aldryn-people==1.2.2

So django-phonenumber-field isn’t pinned adequately in Aldryn People.

The solution is to pin any packages to versions that have compatible dependencies, either in theproject’s requirements.in, or (if possible) in the setup.py of the other packages thatinstalled them:

  1. django-phonenumber-field<2.0.0

Locally, the project can be tested for dependency conflicts of this sort by runningdocker-compose build web.

原文: http://docs.divio.com/en/latest/how-to/debug-dependency-conflict.html