CocoaPods could not find compatible versions for pod "firebase_auth": In Podfile: code example
Example 1: CocoaPods could not find compatible versions for pod "Firebase/Messaging":
I had the same problem, but I solved it like this
rm Podfile.lock
pod install --repo-update
Example 2: cocoapods could not find compatible versions for pod cloud_firestore
# platform :ios, '9.0'
change to
platform :ios, '10.0'