In New Relic Ruby agent version 6.0.0, a number of APIs that were not publicly supported were deprecated or deleted. If you use any of the deleted methods, you must update your API with the recommended replacement before upgrading to Ruby agent version 6.0.0 or higher. If you use any of the deprecated methods, we recommend updating your API as soon as possible to ensure compatibility with versions of the agent higher than 6.0.0.
Solution
Update your API with the following recommended replacements:
Replace with NewRelic::Agent::Tracer.start_external_request_segment
Replace with NewRelic::Agent::Tracer.start_segment
Replace with NewRelic::Agent::Tracer.start_transaction_or_segment
Replace with NewRelic::Agent::Tracer.start_datastore_segment
Replace with NewRelic::Agent::Tracer.start_segment
Replace with NewRelic::Agent::Tracer.in_transaction
Replace with NewRelic::Agent::Tracer.current_transaction