"Your project does not explicitly specify the CocoaPods master specs repo" warning when running pod install

When running the 'pod repo remove master' I was greeted with:

[!] repo master does not exist

I did a ....

pod repo list

cocoapods
- Type: git (master)
- URL:  https://github.com/CocoaPods/Specs.git
- Path: /Users/plasma/.cocoapods/repos/cocoapods

trunk
- Type: CDN
- URL:  https://cdn.cocoapods.org/
- Path: /Users/plasma/.cocoapods/repos/trunk

Noticed the 'master' is actually called 'cocoapods' so then I did a..

pod repo remove cocoapods

One that had completed I was able to do update and install without any errors.

Run the command pod repo remove master

I would recommend following Plasma's answer. However, if you don't want to delete the master repo, just mute the warning by adding the warn_for_unused_master_specs_repo setting to your Podfile by changing this:

install! 'cocoapods'

to this:

install! 'cocoapods', :warn_for_unused_master_specs_repo => false

If you already have an option after install! 'cocoapods', append the new setting with a comma:

install! 'cocoapods', :deterministic_uuids => false, :warn_for_unused_master_specs_repo => false