The Los Angeles County Registrar-Recorder said that the names of 118,522 voters were omitted from the voter roster because of a random printing error.
Poll workers use the roster to check in voters at their polling place.
In an interview, a spokesman with the county registrar said the office did not know what parts of the county were affected, but some 1,530 precincts of the 4,357 Los Angeles County voting locations were impacted.
"We are working to see what precincts are affected," said Michael Sanchez, a spokesman with Los Angeles Registrar, who explained that the office had discovered a random printing error on the roster.
"We don't know yet. We are still in the thick of it."
Voters whose names did not appear on the roster were supposed to be given provisional ballots, but clearly that did not happen in some cases. The department received calls and complaints throughout the afternoon, several hours before polls closed.
While all registered voters can still cast a provisional ballot before the polls close at 8 p.m. PT, the irregularity could potentially cause major headaches in counting votes in the governor's race and the highly competitive contest in the 39th Congressional District, which is represented by retiring Congressman Ed Royce.