up in arms

up in arms (angry, rebellious) — охваченный восстанием; готовый к борьбе; готовый к сопротивлению; в полной боевой готовности; возбуждённый; злой; готовый к бою; воинственно настроенный (Multitran)

Example 1: World's poor are up in arms over food prices. (newscientist.com)

Example 2: Shortly after Flickr added videos to its photo-sharing site, a number of users are up in arms. The No Video on Flickr group amassed more than 4,000 members just a few hours after the new feature launched. (news.cnet.com)

Example 3: Up in Arms about Media Bias (When It's Convenient). (britannica.com)