I am trying to migrate from 1.2.x and earlier thread in which I had asked about python version, I was told that it will be 2.7 for some time longer.
I now face the problem that “pip install indico-migrate” is asking for python v3.4. The last few lines are pasted below.
Collecting pathlib (from pyScss==1.3.5->indico<2.1.dev0,>=2.0->indico-migrate)
Downloading https://files.pythonhosted.org/packages/ac/aa/9b065a76b9af472437a0059f77e8f962fe350438b927cb80184c32f075eb/pathlib-1.0.1.tar.gz (49kB)
100% || 51kB 2.9MB/s
Collecting validators>=0.5.0 (from WTForms-Components==0.10.3->indico<2.1.dev0,>=2.0->indico-migrate)
Downloading https://files.pythonhosted.org/packages/d9/1f/27dff5c1ea8f36865a179581dea4f75d1ab52cd8f32ee527a592b6558b55/validators-0.17.0.tar.gz
validators requires Python ‘>=3.4’ but the running Python is 2.7.5
How to get over this?
Nagaraj
That’s usually because some dependencies of dependencies broke in the meantime - something that inevitable happens when trying to install an outdated version (Indico 2.0), which is exactly why we really encouraged people to migrate from 1.2 shortly after 2.0 was released! 
Anyway, I’m afraid I cannot reproduce your problem. I just created a new virtualenv with Python 2.7, and after installing the old pyatom version (using the command here) I was able to pip install 'indico<2.1' and then pip install indico-migrate just fine…
My guess would be that, since you are on Python 2.7.5 (the ancient version coming with CentOS…), your pip and/or setuptools are ancient as well. Upgrade them using pip install -U pip setuptools and then try installing indico and indico-migrate again. Old versions of these tools do not know how to filter out packages not compatible with the current Python version.
Hi,
You mention that
I just created a new virtualenv with Python 2.7, and after installing the old pyatom version (using the command here) I was able to pip install 'indico<2.1' and then pip install indico-migrate just fine…
Can you please tell me what on what platform/OS you checked it out as above? I will try out identical. Thanks a lot!
That was on my development system (Gentoo Linux) where I have Python 2.7.18. Not a setup you want to replicate.
Anyway, your 2.7.5 should be fine as long as you upgrade pip and setuptools inside the virtualenv (we actually have 2.7.5 as well on our CentOS7 servers in production).