Instagram said on Thursday it accidentally rolled out a design change to a large number of users and quickly ended the test after complaints from users of the Facebook-owned social network.

The redesign required users to swipe horizontally instead of the normal vertical scroll to see their feed, befuddling many members of the photo- and video-sharing application, which has over one billion users worldwide.

The move ignited complaints on Twitter where the hashtag #InstagramUpdate became a top trending issue.

Twitter user Jeffree Star lamented “this #instagramupdate almost ruined my morning!!” while journalist Alex Heath of the online service Cheddar remarked that it “seems maybe intended to reduce mindless vertical scrolling?”

Adam Mosseri, who heads Instagram for Facebook, tweeted that the new design was “a test that went to a few orders of magnitude more people than intended.” “Sorry about that.”

Instagram said a short time later that it had rolled back the redesign to the normal vertical scroll.

“Due to a bug, some users saw a change to the way their feed appears today,” said an Instagram message posted on Twitter.

“We quickly fixed the issue and feed is back to normal. We apologize for any confusion.”

Some Instagram users remained upset over the glitch. “Never do it again pls “: tweeted one enraged user.