On mac OS Catalina, for Fastlane, I am seeing an error whenever I try to run any Fastlane command.
"nokogiri.bundle" can't be opened because its integrity cannot be verified
I researched and found that the mac os gatekeeper was blocking this as it treats it as an unidentified developer.
A similar issue was reported on Fastlane GitHub issues for ruby. https://github.com/fastlane/fastlane/issues/15186
To allow execution
Goto System Preferences -> Security & Privacy and agree to run the app