INDIANAPOLIS (AP) — Some Indiana school officials say students faced frozen screens and error messages during a test run of the online ISTEP exam.

Wayne Township Schools superintendent Jeff Butts says many students in the suburban Indianapolis district faced technical troubles during Wednesday’s readiness test. A new contractor handled the assessment. Butts tells The Indianapolis Star that students can’t afford to have such problems during a timed exam.

Greenwood schools officials say they sent students back to class when the readiness test wouldn’t load.

Pearson Education is running the ISTEP exam that begins in February under a $33 million, two-year contract. Pearson spokesman Scott Overland says the practice test is designed to stress the system so problems can be corrected.

Similar glitches occurred under previous vendor CTB/McGraw Hill.