Windows10 ImportError: Failed to import libcppyy3_7. Please check that ROOT has been built for Python 3.7

Newbie
1

I have ROOT 6.24.00 installed on Windows 10 through Anaconda3 complied against VS2019 and python 3.7.9. I get the above error

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

when I try and import ROOT in Spyder5. I can’t call root from the anaconda prompt at all. I can check

root-config --python-version

from the anaconda prompt and it says 3.7.9. Anyone have any thoughts? I’m stumped.

2

Hi @Kittyk123,

I can only suspect that either libcppyy3_7.dll or libcppyy_backend3_7.dll cannot be found in the library search path. However, I am sure that @etejedor can provide a more detailed answer.

Cheers,
J.

3

Hi,

That should not happen when installing via conda, I’ll check with the package maintainer and get back to you.

4

The ROOT conda package maintainer informed me that there are no Windows binaries for ROOT in conda-forge as 32-bit Python isn’t supported.

Is it possible that you are using a ROOT installation that you built yourself?

5

Yeah, I built root myself following the Github instructions to make sure it was complied against the right Visual Studio (I have 3 versions on my computer) and my version of Python. I question if the problem is my Anaconda installation since I have had previous issues calling Python from MATLAB and vice versa, but I worry about changing my Anaconda installation because I have projects for another lab I work in on my computer as well.

6

Hi @Kittyk123,

If you built root yourself, some environment variables might not have the correct value (namely search paths). Try running the thisroot.bat script included on your build/install directory on a cmd.exe session. Reuse the same cmd.exe session to start the python interpreter and issue:

import ROOT

Let us know if that workarounds your problem.

Cheers,
J.