The state's student grant processing system has come under fire after it crashed ahead of the deadline for applications.
The Student Universal Support Ireland (Susi) was forced to extend its deadline for online applications until midnight on Monday.
A last-minute surge of applicants for third-level grants led to congestion on the site causing a technical error, which resulted in the system shutting down from 7pm to 9pm before its midnight deadline on Thursday.
"It is very disappointing that yet again there has been a glitch in the Susi system, which was caused due to a surge in applications last night. It should not have come as any surprise to the student grant body that there would be a spike in online traffic ahead of the deadline," Mr Harris said.
"This should have been anticipated and adequately planned for."
Susi was set up last year as a centralised system to replace applications to different local authorities across the country. Thousands of students were left waiting for months for their grants to be paid last year due to a delay in the processing of their applications.
Mr Harris said such "teething problems" were to be expected in the early stages of a new system, but he does not want to see a repeat this year. Extra staff members have been drafted in to ensure all grant applications are processed on time.
"Last night's system crash mainly affected first time applicants, most of whom will be keen to submit their grant applications before they get their Leaving Cert results in less than two weeks," Mr Harris added.
"Susi must look at whether the deadline for online applications has been extended far enough to deal with the surge in traffic. There is no point imposing a deadline if students cannot access the website in the first place."