Bob Laszewski, a health care consultant who works closely with insurers, estimated that the site’s back-end error rate is 5 percent. It needs to be lower than 1 percent for the site to be considered fixed, he said.

“They’ve made some progress on the back end, but it’s still not where it needs to be,” Laszewski said.

Some health policy experts also question the administration’s definition of success for the site’s user experience.

Administration officials have said they expect the site will work for about 80 percent of users by Nov. 30. Yet a 20 percent failure rate wouldn’t be considered success in most industries, and it also might not be good enough to stem the tide of negative anecdotes about Obamacare enrollment.

“Twenty percent still leaves a lot of noise in the system … that leaves a lot of people with a bad experience,” said Caroline Pearson, vice president at the consulting firm Avalere Health.