Rule reminder
Common errors with exceptive clauses: (1) using indicative instead of subjunctive after 'a meno che'; (2) omitting 'che' after 'tranne/eccetto/salvo' before a verb; (3) confusing exceptive 'a meno che' (unless) with restrictive 'purché' (provided that); (4) using 'non' where it is not expletive but truly negating; (5) wrong tense sequence in the subjunctive.
Which sentence contains an error?