How to download a complete macOS High Sierra installer app

Recently my sister asked me to reinstall the macOS High Sierra on her iMac because it stopped working correctly. I thought that it would be easy to do but I was mistaken. I successfully installed the macOS Mountain Lion (when using the NetBoot it automatically selects the version of macOS with which the iMac was shipped with). But then I was facing multiple issues trying to update macOS from Mountain Lion to High Sierra via the Mac App Store.

How to fix: The volume can't be ejected because it's currently in use

After working with an external hard drive (further simply - disk) I want to cleanly unmount it. But to my surprise when pressing the ‘eject’ button Finder warns me with the following error messages:

The volume can't be ejected because it's currently in use.

How to fix: fatal: Authentication failed for https://github.com/

After enabling a two-factor authentication in my GitHub account, when I run the Git git push command it throws the following error message:

$ git push
Username for 'https://github.com': Username
Password for 'https://Username@github.com':
remote: Invalid username or password.
fatal: Authentication failed for 'https://github.com/username/repository.git/'

How to fix: MediaKit reports not enough space on device for requested operation

Today I bought a brand new external hard drive WD Elements Portable 1Tb. A Western Digital company says that it can be used on both Windows and macOS. But most WD drives come formatted in the NTFS file system format for OS Windows, while for macOS we needed the HFS+ format or the Apple’s brand new APFS (Apple File System) format.

How to fix: bundler: command not found: jekyll

We can set up a local version of our Jekyll GitHub Pages website to preview our website before making the changes public. But after upgrading MacOS to version “High Sierra” on my MacBook, when I run the jekyll bundle exec jekyll serve command it throws the following error message:

$ bundle exec jekyll serve
bundler: command not found: jekyll
Install missing gem executables with `bundle install`