Saying that developers must take a "hard look at our blocker list," Nightingale added that, "at this point, very few bugs are worth holding back that much awesome."

Nightingale said that as of Thursday, 143 hard blocker bugs remained, and detailed which flaws fit into the category. "A hard blocker is a failure of a core part of our release criteria, e.g. a crash, a memory leak, a performance hit, a security issue, a [user interface] breakage that can't be recovered from, an incompatibility we can't stomach," he said.

It's unclear if Mozilla will do a 10th beta.

Although Firefox Beta 10 remains on a that shows on Mozilla's Web site, on Monday Damon Sicore, who leads the company's engineering group, hinted that Beta 9 might be the last.

"If we can't get [bugs] to zero in reasonable time, we'll repeat [a tenth beta]," he said on a Firefox developers .