A pilot of the online literacy and numeracy test is in disarray, with the Victorian, Western Australian and ACT governments announcing on Wednesday that they would withdraw from the trial and South Australian and Queensland ditching it earlier this month. 

NSW, Tasmania and the Northern Territory had always planned to roll it out at a later stage.

The online trial was due to start next month, but Victorian Education Minister James Merlino said technological issues had not been resolved. 

"Recent testing indicates that this could affect students' ability to complete the tests," he said. 

"We want NAPLAN Online to be a positive experience for students and schools. With three weeks to go, we don't have enough time to be confident of this happening."

"The last thing we want is students being unable to demonstrate their numeracy and literacy skills because of technological faults."

All Victorian students will instead sit pen and paper tests this year. 

Mr Merlino said that the state government would work with Education Services Australia and other states to ensure that the online test was successfully rolled out from 2018. 

Power failures, freezing, browser issues and broken internet connections plagued initial trials of the online NAPLAN tests, according to a report by primary school principals who were involved in administering the online tests.

The online test will be gradually rolled out over a three-year period, and about 10 per cent of schools were initially expected to take part in its trail this year.

The Australian Curriculum Assessment and Reporting Authority chief executive Robert Randall said it was disappointing that the five states and territories were no longer moving to online NAPLAN in 2017. 

"I respect the decision of states and territories to delay transition to allow more time to gain a greater level of confidence for the move online," he said.

He said states and territories were determining which schools would take part in a separate readiness trial in August/September.

The switch to online testing will mean speedier results for parents and schools.

Schools currently have to wait about 12 weeks before receiving results from the pen and paper tests. 

The online test will also be adaptive, with questions adjusted according to students' skill levels. 

When Queensland announced that it was pulling out of the trial, Federal Education Minister Simon Birmingham said he hoped that other states still took part in the online tests.

Australian Principals Federation president Julie Podbury said NAPLAN online would be a "useful tool" for schools, but there was no use rolling out a product if it was not going to work. 

"You can't afford to waste time in schools, principals and teachers work hard enough ... so let's ensure it is 100 per cent right before we roll it out," she said.

President of the Victorian Association of State Secondary School Principals Judy Crowe said principals participating in the trial said they were disappointed by the news.

They looked forward to receiving faster feedback on students' performance on the test - a key advantage to the online model - but they accepted the test has "technical issues", she said. 

"The platform has to be absolutely workable," said Ms Crowe. "There have to be minimal risks that things will go wrong."

Ringwood Secondary College principal Michael Phillips, whose school was set to take part in the online test in May, said the news was "disappointing".

"In 2017 we have all this technology that kids are using all the time and yet we can't get it right," he said. 

The state school in Melbourne's east had a positive experience when it experimented in a smaller trials of online NAPLAN last year. 

It has invested time in making sure the tests ran smoothly, and just yesterday, ran a briefing for 100 staff.