Sorry — didn’t mean to fire you!

Yahoo! CEO Marissa Mayer accidentally started swinging the ax last week, as bureaucratic snafus resulted in dozens of employees losing their jobs, sources told The Post’s James Covert.

“They put people on firing lists who they didn’t mean to — people who were lower on the performance scale but who weren’t meant to get fired,” an insider explained. “But no one told the managers, and then they had the conversations, and it was like, ‘Oops.’ ”

The screwups — which may have affected as many as 30 employees, according to one source — didn’t go over well with some team supervisors, according to insiders.

“This is the only person who does this job — how could you do this?” was a common complaint, a source said.

“There is zero truth to this rumor,” a Yahoo! spokeswoman commented.