"It has taken nearly a week."

[peter2108]

Ci è voluto quasi una settimana is flagged as wrong. Is it?

EDIT. One native speaker says it's Ok. Another that it's grammatically correct "but sounds odd"

[f.formica]

Well, when conjugating the passato prossimo with a personal pronoun the past participle should take the gender and number of the object, although it isn't a strict rule; this case is different as "volerci" doesn't include a personal pronoun, "ci" here is more of a (generic) place adverb. I think the participle takes the gender of the object more as similitude with the pronoun case that for any rule; just like in that case, "c'è voluta una settimana" sounds much more natural than "c'è voluto una settimana", but the latter is grammatically fine.