You can revert to the previous version of software using the request system software rollback command in the CLI. For the changes to take effect, you must reboot the router. To downgrade to an earlier version of software, follow the procedure for upgrading, using the JUNOS software image labeled with the appropriate release.
To downgrade software with the CLI:
The previous software version is now ready to become active when you next reboot the router.
The router is now running the previous version of the software.