Victorian Curriculum and Assessment Authority CEO Kylie White resigned one day after the state government ordered a sweeping review of the body, which has been plagued by years of errors in final assessments.
The exam authority uploads sample exam papers each year to familiarise about 50,000 students with test details, but it has since emerged that tech-savvy pupils could spot hidden questions.
Some 56 of the state's 166 VCE exams were affected by the error, Education Minister Ben Carroll revealed on Monday.
The issue impacted a "major part" of at least two exams, and one or two multiple choice questions in others, with no complete papers published in full.
The issue was identified before the exam period started and in several instances, the rewrites were "incredibly minor" and unsatisfactory.
That's in stark contrast to Ms White's insistence last week that the issue did not compromise any final exams.
"I'm incredibly upset and angry," Mr Carroll said on Monday.
"I was given reassurances that the exam questions that had inadvertently been released and uploaded with the instruction cover sheets had been rewritten and that has proven to be completely unsatisfactory."
Mr Carroll characterised it as "a publishing error overseen by human error" and said measures were in place to ensure no student would be unfairly disadvantaged.
The authority will use an existing grade check process, overseen by an independent advisory panel of experts chaired by Professor John Firth, for the impacted exams.
Answers will be reviewed to identify anomalies in how students responded to affected questions and marks adjusted if they provided anyone with an unfair advantage.
This means some questions could be ruled invalid, resulting in the students who sat those exams being awarded full marks.
Education officials are still working towards releasing results in mid-December as planned.
Mr Carroll apologised to the students.
"The last thing our year 12 students need is additional stress and uncertainty from the administration of examinations," he said.
"We're taking action and taking the right steps to ensure that no student is disadvantaged in the marking of the 2024 examinations."
Multiple errors appeared in general maths and chemistry exams in 2023 and six students received the incorrect Chinese language exam.
Five questions from the 2022 maths exams also contained errors.
An independent review, led by former NSW Education Standards Authority head John Bennett, was ordered in 2022 and made six recommendations, including hiring more suitably qualified academics to develop exam papers.
Victorian Academy of Teaching and Leadership chief executive Marcia Devlin has been named interim replacement for Ms White, pending a permanent appointment.
Opposition spokeswoman Jess Wilson accused Mr Carroll of being "complicit in the cover-up" after the minister revealed he was made aware of the issue on October 14.
The Victorian Opposition will introduce a motion in parliament next week to refer the issue to the state's Ombudsman for further investigation.
"We have seen now a guarantee, supposedly, that no student will be at a disadvantage. But how can we trust VCAA to do so after the debacle we've seen over recent weeks?" Ms Wilson said.
She called for students to be able to access information about how their own exams are marked.
"Only through that process is there going to be a shred of confidence from students that their marks are the marks that they deserve," Ms Wilson said.
The Australian Education Union backed the efforts to address student disadvantage.
