How to install a specific version of ERPNext

[yashodhan]

@Zia_Akbari

raise CommandFailedError(cmd) bench.utils.CommandFailedError: frappe-bench-v9/env/bin/pip install -q -e frappe-bench-v9/apps/frappe --no-cache-dir

When this happens, it is usually found that some python dependencies are missing or not installed properly by pip
it happens due to recent pip version upgrade is responsible for broken packages.

Find right pip version to install older versions of Frappe/ERPNext dependencies anything before v8 works good with pip version <= 9.0.1

some other findings:

Pip error: command 'x86_64-linux-gnu-gcc' failed with exit status 1

Issue Installing collected packages: mysql-python, python-geoip, python-geoip-geolite2, python-dateutil, pytz, termcolor, werkzeug, semantic-version, rauth, redis, selenium, babel, scandir, pathlib2, pickleshare, simplegeneric, enum34, decorator, ipython-genutils, traitlets, backports.shutil-get-terminal-size, pygments, ptyprocess, pexpect, wcwidth, prompt-toolkit, ipython, html2text, email-reply-parser, click, num2words, PyYAML, argh, pathtools, watchdog, webencodings, html5lib, bleach, bleach…

ImportError: No module named req | bench init unable to install version frappe 7.x.x

Issue bench’s install.py / setup.py from apps does automatically upgrades pip package itself causing lot of issues dependencies installation as well as ERPNext. I found out that degrading version to 9.0.3 works with older Frappe-ERPNext versions well (anything below v9) but for latest versions v10 and upcoming v11 you need lates pip version 10/18 to load all required packages and internal python libraries. For Frappe/ERPNext from version 7 to 9 : pip version 9.0.3 happens to work smooth setu…

This is an issue open at bench repo, causing pip upgrading to version 18 while init or install resulting in error while dealing with older versions of Frappe/ERPNext using Bench.