[fix] Flutter: CocoaPods could not find compatible versions for pod "Firebase/Messaging"

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I was able to solve similar error by updating the target iOS platform to 10.0. Update the platform configured in the Podfile to platform :ios, '10.0'. I've also had to update the iOS Deployment Target to 10.0 - located on Runner > Info > Deployment Target

After that, deleting the Podfile.lock with rm -rf Podfile.lock then running pod update and pod install solved the issue for me.