A survey reveals 23 per cent of primary school principals, who are among those administering the online test for the first time next year, will not be up to the task by May 2017.

They are still grappling with basic challenges such as maintaining power and an internet connection, with a survey of nearly 200 principals finding an alarming 84 per cent faced problems with technology during initial trials of the test.

One school was forced to connect all devices by extension cords to maintain power on the students' devices, posing a safety problem for students and supervisors moving around the classroom.

The Australian Primary Principals Association survey said schools were crying out for more technical support and staff training to prepare for the test.

They said internet connections were dropping in and out, the test overloaded the school's bandwidth, and students were losing work, or not being able to review completed tests.

Principals called for "further investigation and research" into whether iPads were a suitable device for the tests, with many freezing for a short time, some requiring to be rebooted, while students had trouble logging on and downloading the test on the tablet.

The association's president Dennis Yarrington said the organisation was in talks with the Australian Curriculum, Assessment and Reporting Authority about developing a contingency plan for schools if technical difficulties arose during the exam.

"What's the Plan B if there are technical or connectivity problems on assessment day? That needs to be one sorted and put in place," he said.

"We need to ensure when schools sign up to do NAPLAN online, that they will be fully supported in the implementation of the test."

Principals said they would need to improve students' keyboard and desktop navigational skills before the test, while students who had less access to computers at home found the online format more difficult.

The online test will be gradually rolled out over a three-year period, with about 10 per cent of schools moving online next year.

The curriculum authority indicated in a recent newsletter that initial trials had been "mostly positive" and concerns expressed in the survey did not reflect the experience of most schools participating in  its tests.

The authority's chief executive Robert Randall said technical problems were expected during the trial period.

"We were pleased with how the platform trials went for NAPLAN online. As expected with any trial of new technology we identified some technical issues. Those issues can now be addressed to ensure we are ready to move NAPLAN online from next year."