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1- Check the minimum release: https://www.juniper.net/documentation/en_US/cso5.0/information-products/topic-collections/release-notes/5.0.0/jd0e64.html#jd0e247
2- Upgrade/downgrade the SRX ( if needed)
3- zeroize the configuration
4- create an site on the Cloud CSO
Onboard vSRX on NFX250:
1-