Instagram users found a surprising update when they went to check out some holiday photos Thursday morning: They now need to scroll or tap through their feed horizontally.

Shortly after the release, Instagram's Head of Product Adam Mosseri tweeted that it was meant to be "a very small test but we went broader than we anticipated." Many Instagram users reported that their feeds went back to the original vertical scrolling.

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The Facebook-owned photo-sharing service introduced the feature Thursday morning with instructions in the app to "Tap through posts, just like you tap through stories," referring to the Snapchat-style sharing feature where photos can disappear after 24 hours.

Like many major updates to popular technology, this one faced quick backlash from users, even if it lasted only briefly. On Twitter, #instagramupdate was the No. 1 trending hashtag in the U.S. on Thursday morning, where people complained that the new feature makes it harder to scroll past posts they don't care about, including advertisements.

In a statement, Instagram said, "Due to a bug, some users saw a change to the way their feed appears today. We quickly fixed the issue and feed is back to normal. We apologize for any confusion."

Many compared the update to the ill-fated Snapchat redesign that even inspired a petition of over 1 million signatories earlier this year. Snap, the company that owns the app, actually ended up redoing its redesign shortly after the release, and CEO Evan Spiegel later acknowledged that the entire project was "rushed" in a memo to employees.

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