Binaries for ROOT 6.22 not built with python3 support


On the release page for 6.22 I read

ROOT can now be built against Python3 and Python2 at the same time , creating the necessary libraries for import ROOT to work from both python2 and python3 , for a single ROOT build. Most of the binaries below now offer this.

However, it seems the build for ubuntu 19.10 does not support python3. When trying to import ROOT in python3 I get:

Failed to import libcppyy3_7. Please check that ROOT has been built for Python 3.7

While it works fine in python2.

I’ll move to compiling the release myself, but it would be nice if the packages worked out of the box.


ROOT Version: 6.22.0
Platform: ubuntu 19.10
Compiler: GCC 9.2

thanks for the feedback! Maybe @etejedor can comment on the current status of the binary releases.

Instead of compiling ROOT from scratch, however, I would suggest installing ROOT as a conda package.


Hi @swertz ,

The Ubuntu19 binaries are indeed only distributed with Python2, since we will soon discontinue its support (19 is not LTS).

The Ubuntu20 binaries, on the other hand, have both Python2 and Python3.

Link to a relevant ticket:

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Thanks for the replies!

Ok, I’ll take to opportunity to make the switch now to 20.04 then…

It could be useful to include the table from the bottom of the ticket, indicating which python versions the various releases support, to the release page?

Thanks, I can see why that is useful is some cases, but if someone just needs ROOT to work on a laptop, e.g. to open root files in a browser from time to time, not to develop in a full python scientific/ML stack, then installing the hundreds of extra packages with conda (many of which are duplicates of system packages) is a bit wasteful…

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