The humbling reversal on one of the most sensitive policy issues facing the social network came as Twitter encountered user revolt for the first time as a public company. Under the short-lived change on Thursday, a blocked Twitter user could view or tweet at the person who blocked him or her, but that activity would have been rendered invisible to the victim as if the offending account did not exist. Under the re-instated policy, users could prevent their harassers from following them or interacting with their tweets. Users are also explicitly notified if they are blocked. Before it backtracked, Twitter had said Thursday that the change was meant to protect victims of harassment who wanted to filter out abusive messages but feared that the act of blocking a user would prompt retaliation. "We have decided to revert the change after receiving feedback from many users - we never want to introduce features at the cost of users feeling less safe," vice president of product Michael Sippey wrote in a blog post. Chief Executive Dick Costolo initially sought to address the mounting criticism by saying on Twitter that the new features were widely requested by victims of abuse. But many were not convinced. Within hours, the service was flooded with angry users, including many who did not understand the nuances of the new policy, and hundreds had signed an online petition to reverse the change. "New @twitter block policy is like a home security system that instead of keeping people out puts a blindfold on YOU when they come in," said user @edcasey.
"'Just ignore them & they'll stop' is a dangerous thing to say to bullied kids & a dangerous thing to say to stalked/harassed Twitter users," wrote @red3blog, another user.
Keeping abuse in check is a key issue for the company, which needs to keep hold of existing users and attract hundreds of millions of new ones to justify the stratospheric valuation that investors have placed on its stock.
Twitter shares have risen 35 percent to $55.33 the past two weeks on investor expectations that the company can sustain its growth for years and mature into an internet powerhouse.
The changes were announced Thursday after the market close.
The company's swift about-face similarly drew an outpouring of relief.
"The people have spoken and Twitter listened, thanks," said user @samar_ismail.
The controversy highlighted Twitter's dilemma over how it should police the freewheeling service or stamp out abuse.
Twitter, which once espoused a radically hands-off approach to moderating content, was pressed in August to strengthen its "report abuse" functions after two high-profile women in the United Kingdom, feminist and journalist Caroline Criado-Perez and Labour Party politician Stella Creasy, were subjected to a deluge of death and rape threats.
Twitter's top executive in the U.K., Tony Wang, and Del Harvey, the head of its trust and safety team, issued personal apologies to the women after revising Twitter's rules.
Twitter said Thursday that the company's policies were still evolving and that the block feature remained problematic because some users were fearful that their harassers would be notified when they become blocked.
"Moving forward, we will continue to explore features designed to protect users from abuse and prevent retaliation," Sippey, the Twitter executive, wrote.
"We've built Twitter to help you create and share ideas and information instantly, without barriers. That vision must coexist with keeping users safe on the platform."
The backlash was a rare event for a company that for the most part has been hailed for championing its users, who now number more than 250 million worldwide.
Although Twitter has made unpopular design tweaks, it has maintained a better policy record than social media rival Facebook Inc, which has repeatedly upset users with abrupt changes to its privacy policies.