A lock system upgrade was performed in the upperclassman residence hall City Hall last week, a change that triggered some residents’ key cards to deactivate.

“An upgrade was performed to existing locks used in City Hall at the request of the lock manufacturer,” University spokeswoman Michelle Sherrard said.

The upgrade, which took about five minutes per unit, replaced a metal piece of each lock with stainless steel, she said.

Although Sherrard said the upgrade would not disrupt residents, some complained that their keycards had been deactivated since the change. The room doors in City Hall are controlled by magnetic cards, not keys like the University’s other residence halls.

“The lock wouldn’t accept my roommate’s or my key. We had to call emergency Fix-It and it took about two hours for them to respond,” Desi Kireva, a junior living in City Hall, said.

Of the 370 living in City Hall, just 20 to 25 reported problems with deactivated key cards. Most were unaware of the procedure and had no trouble getting into their rooms.

Megan Krentsa and Tim Dalferro, both juniors in the residence hall, said they only knew the locks had been changed when they received an e-mail from the Key Depot explaining how to trade in deactivated keycards.

Students expressed concern about how accessible the residence hall is to outsiders.

“My friends and I have had some problems with being followed by a man who constantly hangs out in front of the building,” Kireva said.

All three students agreed that entering the building without a keycard is relatively easy, a concern that has recently led the University to station a police officer at the entrance of the West End residence hall. Last week a man allegedly entered the sophomore building, threatened a female student and hit others.

“It isn’t difficult to piggy-back into the dorm. Most people just walk up behind someone swiping in and follow through the open doors,” Dalferro said.

The University announced in February that it will not renew the lease on City Hall after GW’s contract on the building expires in 2016.