Computer problems have plagued a popular online college application system, causing admissions delays. But operators of the program said Thursday that they had fixed a large chunk of the problem.

After a rocky roll-out of a new online computer program, the Common Application said it fixed two big snags that had left students across the country struggling to file applications before early admission deadlines.

The Common Application allows students to apply to multiple schools at once; more than 500 colleges and universities accept it, and it is run by a nonprofit with the same name.

It has been inundated with user complaints about technical glitches since a new online system was rolled out Aug. 1. Some students have complained about being unable to log in and to tell if their payment had been accepted. College admissions offices have had problems retrieving documents they need within the system.

In response, some colleges and universities such, as Northwestern University in Evanston, Ill., and the University of North Carolina at Chapel Hill, N.C., have delayed early admissions deadlines.

Scott Anderson, senior director for policy with College Application, said the organization made two major fixes to problems Wednesday night. One fix related to payment problems and the other to difficulty some students had using the system with a Chrome browser.

Anderson said they anticipate about 800,000 students will use the Common Application this year — about a 10 percent increase from last year — and already more students have successfully submitted applications this year than last year at this time.

“For applicants going forward, I think we really have addressed the major issues that they are seeing,” he said.

Ashley Memory, senior assistant director of admissions at the University of North Carolina at Chapel Hill, which extended its early action deadline to Monday, said the admissions staff already has noticed that things have been going better since Wednesday. She said they are having daily meetings to discuss the situation and could extend the deadline again if necessary, but they are hopeful they won’t need to.

“We have noticed that things have been going smoother, and we have been able to upload about 10,000 applications into our system,” Memory said.

On Thursday, however, many students were still posting complaints on the organization’s Facebook site related to technical problems. Some were advising others to submit an application in the middle of the night to avoid problems.

Ruth Lohmeyer, a school counselor at Lincoln Northeast High in Lincoln, Neb., said she’s telling her students not to take any chances. She’s warning them to give themselves plenty of time to submit an application.

“The process will take longer,” Lohmeyer said.