Covered California spokeswoman Anne Gonzales said the errors on the list stemmed from inaccurate information about individual physicians provided by the insurance plans themselves.
She also said the exchange became aware of the errors from "anecdotal" stories, and "through social media."
"We understood that there were people that had bought a plan based on a specific provider and then would call the plans and find out the provider was not in that network," Gonzales said. She did not know the total number of consumers that had such problems.
Covered California urged enrollees to contact their insurer "to verify the provider is in the network, or to ask for a different provider in their area." Gonzalez said enrollees also should double-check with the providers themselves that they actually are in a plan's network.
"If enrollees find the resolution unsatisfactory, they can contact Covered California's service center to ... enroll in a different plan before the end of the open enrollment period, March 31."
The exchange will still give consumers electronic links to the provider directory for each plan. However, those individual directories themselves were the source for the errors on Covered California's master list of available doctors, said Gonzales.
"We're working with our plan partners to get the most reliable and accurate information" on those individual directories, she said.
Covered California had planned to add a list of hospitals accepting insurance sold on the exchange, but that is now on hold indefinitely, said a spokeswoman, adding that there is no projected date for reposting the doctors' list.
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In a story published Friday, the Los Angeles Times detailed the frustrating experience of Danielle Nelson, a California resident who told the paper that Anthem Blue Cross had reassured her that her oncologist, who was treating her non-Hodgkin's lymphona, was covered by the policy she bought from the insurer through the state's exchange.
But when she visited her oncologist, she saw a sign prominently announcing that the office was not accepting Covered California plans, the Times reported.
"I'm a complete fan of the Affordable Care Act, but now I can't sleep at night," Nelson told the newspaper. "I can't imagine this is how President Obama wanted it to happen."