Error when trying to install Firebase with pod relative to nanopb

According to https://github.com/CocoaPods/Specs/blob/master/Specs/8/b/d/FirebaseCore/4.0.4/FirebaseCore.podspec.json, nanopb is added in dependencies on FirebaseCore 4.0.4.

But nanopb server is not working now.(http://jpa.kapsi.fi/nanopb/download/nanopb-0.3.8.tar.gz).

So you should specify Firebase/Core version to 4.0.3.

pod 'Firebase/Core', '4.0.3'

I finally add

pod 'Firebase', '4.0.3'

this resolve the problem

yes! so if you retry later, it should work.

Since it is a public repo, an address like https://github.com/CocoaPods/Specs.git.