Hundreds of sections of Reddit, the popular online message board, were unavailable Friday in what appeared to be a protest by many of the site’s moderators after the abrupt dismissal of a high-ranking company employee.
The move affected nearly 300 individual discussion areas — so-called subreddits that focus on individual topics like technology, art and business. Subreddits are generally moderated by self-appointed members of the community, not official Reddit employees. The shutdowns, which began on Thursday evening, appeared to expand rapidly on Friday.
They began shortly after Victoria Taylor, Reddit’s director of talent, was dismissed on Thursday afternoon. On Friday, the volunteers posted a document online that asked for better communication with official staff, as well as improved software tools for community management.
In a telephone interview Friday, Reddit’s interim chief executive, Ellen Pao, said, “I’m sorry we let our community down yesterday.” She added, “We should have informed our community moderators about the transition and worked through it with them.”
The company declined to give a reason for Ms. Taylor’s dismissal, citing a policy of not commenting on personnel matters.
But Ms. Pao said that the company had appointed Kristine Fasnacht as liaison with Reddit administrators — the official employees who work for the company — and the scores of volunteer moderators that oversee subreddits.
Ms. Taylor did not respond to multiple email and telephone requests for comment.
Reddit is usually one of the highest trafficked sites on the Internet, with more than 160 million regular monthly visitors. It is ranked the world’s 32nd most visited site by Alexa, a web traffic analytics site. By the afternoon on Friday, a number of subreddits — including the popular IAmA section — slowly started coming back online.
Ms. Taylor, who had been at the company for two years, was one of the most visible employees of Reddit and handled many of the celebrity question-and-answer sessions that have elevated the site beyond an Internet niche to a platform that draws attention from mainstream media outlets. Reddit’s 2012 interview with President Obama, for example, was linked to by dozens of websites, including The Guardian and The New York Times.
After news of Ms. Taylor’s dismissal was made public, moderators for the “Ask Me Anything” subreddit — one of the most highly trafficked areas of the site — shut it down in a signal of discontent to Reddit’s official employees. One by one, other subreddits followed suit.
Hundreds of messages supporting Ms. Taylor appeared.
“The admins didn’t realize how much we rely on Victoria,” wrote one user, who goes by the username Karmanaut. “We all had the rug ripped out from under us and feel betrayed,” the user also wrote.
Some users drew pictures depicting the former employee as a superhero from the popular comic book “V for Vendetta.”
Ms. Pao gave assurances that there would be a team of employees dedicated to handling the “Ask Me Anything” subreddit, who will work with volunteer moderators.
Aside from inconveniencing regular readers of the site, the closings are likely to impinge on Reddit’s advertising business for as long as they are in effect. Reddit sells large, targeted advertising campaigns that run at the top of individual subreddits.
The events come at a particularly inauspicious time for Reddit, which only a week ago celebrated its 10th anniversary. Last year, Reddit raised $50 million in venture capital, and planned to use the money for hiring and refining the advertising business.
As a private company, Reddit does not disclose its revenues. But the site has been valued at roughly $250 million, according to a recent disclosure by its lawyers. Advance Publications, the parent company of Condé Nast, still owns a majority of the company and retains a board seat.
The company has had its problems over the past year. Yishan Wong abruptly resigned in November as Reddit’s chief executive after a dispute with the company’s board of directors.
Reddit has also taken steps to combat harassment on and off its site, moves that many members of the community complain have stifled the principles of free speech upon which the site was founded.
There has also been tension between factions of the Reddit community and Ms. Pao, whom many Reddit users blame for imposing the anti-harassment policies. An online petition asking Ms. Pao to step down has garnered more than 13,000 signatures.
Reddit users have also questioned Ms. Pao’s ability to lead the company while dealing with major issues in her personal life. For nearly two years, Ms. Pao was embroiled in a well publicized discrimination lawsuit against Kleiner Perkins Caufield & Byers, the venture capital firm. Ms. Pao lost that case in March.
But Ms. Pao says that the most virulent detractors on the site are a vocal minority, and that the vast majority of Reddit users are uninterested in what unfolded over the past 48 hours.
“Most of the community is made up of thoughtful people, and they can appreciate what we all do, even if we don’t always agree,” Ms. Pao said.
Ms. Pao also said that the calls for her to resign — of which there have been tens of thousands from irate users — did not faze her.
“It’s an exciting job,” Ms. Pao said. “We’re doing a lot behind the scenes that people have not seen yet.”
In an interview, Alexis Ohanian, co-founder and executive chairman of Reddit, said: “We definitely hear that we need to make changes when it comes to communicating.”
Mr. Ohanian added, “We haven’t done a great job of that. I hear it, loud and clear.”
An earlier version of a picture caption with this article misstated when the photograph was taken. It was last year, not this week.