Spring break will be an hour shorter this year — but your computer might not know it.

Daylight saving time, which is set by Congress, will now start three weeks earlier than it has in recent years in an effort to conserve energy by maximizing the number of usable daylight hours. But computers, programmed with the previous set of DST rules, will not make the change on their own when clocks spring forward Sunday. Technology experts have said the change could have widespread effects, but Yale has spent the last several months correcting the problem and is not expecting the level of trouble that some have forecast for the rest of the country.

Some computer experts have said the need for upgrades could be considered a “mini-Y2K,” referring to the widespread fears in the late 1990s that computers would not be able to recognize dates after Dec. 31, 1999. But while a team of two dozen ITS employees have upgraded hundreds of computers and servers to fix this year’s problem, Chief Information Officer Philip Long said, the two are hardly comparable.

“Y2K was much bigger in terms of work and much greater consequences of failure,” he said in an e-mail. “Whole systems could stop working or deliver nonsensical results [in Y2K]. DST mistakes will typically be ‘off by an hour,’ not, typically, ‘system fails.’”

Even so, he said the amount of work required to install patches from manufacturers — many of which were routine and included other upgrades — was significant. A total of 16 systems administrators and eight database administrators spent hours on nights and weekends over the last few months installing patches on approximately 600 servers, said Susan Kelley, director of production services and the head of ITS’s work on the DST change. The upgrades covered a substantial portion of the University’s information technology systems, including e-mail, financial and calendar systems, student records, and Web, file and database servers.

ITS has probably not caught all the potential errors the early DST change could cause, Long said. But he expects the impact on the average user to be little more than a nuisance, such as an automatically scheduled program not starting at the proper time or at all on the night of the switch.

ITS has already identified possible problems in the University’s meeting scheduling software, said Andrew Newman, ITS’s director of technology and planning. Meetings and events entered into the system before patches were installed will still be encoded with the wrong time, he said, and some programs will require manual changes.

Since as far back as September, the University has been addressing problems with Meeting Maker, a scheduling program used by more than 3,000 faculty and staff that is run off a Yale server, Newman said.

But possible errors are not limited to a computer’s clock being off by an hour. With computers increasingly linked worldwide over various networks, a computer’s ability to record the correct time internally has become more critical, he said. Daylight saving time in some countries will begin in several weeks, but others have not adopted DST at all.

There have been dozens of changes to daylight saving time since the system was first proposed, and they are nothing to computer administrators, Newman said. The last major change came in 1986, but this time technology experts seem to have been caught off guard.

“A lot of us blithely assumed that this would be no big deal,” he said.

Most technology specialists underestimated the extent of the problem until about four months ago, he said. The law that included the DST changes has been on the books for more than 19 months.

Efforts to head off any problems the changes cause are not limited to Yale. Long said he has heard from peer institutions that they have invested similar amounts of time and manpower in installing software patches.