It fails when I try to do the upgrade. The error messages upon failure was the google fodder than led me to learning about the "3 release" rule. I saved the output of the failure:
SRX210> request system software add /tmp/usb/junos-srxsme-12.1X46-D55.3-domestic.tgz no-validate no-copy
Formatting alternate root (/dev/da0s2a)...
/dev/da0s2a: 297.9MB (610044 sectors) block size 16384, fragment size 2048
using 4 cylinder groups of 74.47MB, 4766 blks, 9600 inodes.
super-block backups (for fsck -b #) at:
32, 152544, 305056, 457568
Installing package '/altroot/cf/packages/install-tmp/junos-12.1X46-D55.3-domestic' ...
verify-sig: cannot validate ./certs.pem
unhandled critical extension: /C=US/ST=CA/L=Sunnyvale/O=Juniper Networks/OU=Juniper CA/CN=PackageProductionRSA_2016/emailAddress=ca@juniper.net
Installation failed for package '/altroot/cf/packages/install-tmp/junos-12.1X46-D55.3-domestic'