Why is "rollback it" incorrect?
Solution 1:
Roll back is a standard phrasal verb. Roll is the verb part, and back is the particle.
Rollback (stress on first syllable) is an event nominalization from roll back (stress on second).
As a phrasal verb, roll back participates in the usual alternation with direct objects:
-
Roll the carpet/budget back. (
Vb + Noun DO + Particle-- OK) -
Roll back the carpet/budget. (
Vb + Particle + Noun DO-- OK) -
Roll it back. (
Vb + Pronoun DO + Particle-- OK) - *Roll back it. (
Vb + Particle + Pronoun DO-- NOT OK)
So there are two reasons why *rollback it is incorrect:
- rollback is a noun derived from roll back, and not a verb itself, so it can't take a direct object.
- roll back is a phrasal verb and must place pronoun direct objects between verb and particle.
Solution 2:
According to the Google dictionary (though not as yet AHD or Collins), the word rollback is also a compound verb (sense (1) here ):
verb (COMPUTING)
verb: rollback; 3rd person present: rollbacks; past tense: rollbacked; past participle: rollbacked; gerund or present participle: rollbacking; verb: roll-back; 3rd person present: roll-backs; past tense: roll-backed; past participle: roll-backed; gerund or present participle: roll-backing
- restore (a database) to a previously defined state.
It is such a recent development from roll + back that 'rollback it' sounds unnatural. 'Rollback X' (X a noun group other than a pronoun) sounds like 'roll back X' which isn't so outlandish. Almost certainly, 'rollback it' will become more common, especially with padding: 'rollback it to the last-but-one state'.
Compound verbs from the fusion of verb + adverb are usually head-second:
downsize; upgrade; outsource; input; overpay
– so the addition of an object, including it, doesn't sound too bad.
It appears that 'voiceover / voice-over' has been analogously verbed.
Solution 3:
"Rollback" is the name of the operation done when you "Roll [a file] Back" to an earlier version. (Usually this is as a part of a change management system).
It isn't a verb. It is a noun made from a verb already. There's no sense in verbifying the noun obtained from nounifying a verb. What would happen when you described that? You could repeat forever.
You either "perform a Rollback Operation or you Roll the file back and call the action Rollback.