2up·set 
/ˌʌpˈsɛt/ verb
up·sets; up·set; up·set·ting /ˌʌpˈsɛt/ verb [+ obj] 1 : to make (someone) unhappy, worried, etc.
▪ That remark you made really upset me. ▪ Don't upset yourself over it. ▪ It upsets him that he can do nothing to help. ▪ A lot of people were upset by the court's decision. ▪ It upsets me to think I might never see him again. 2 : to cause an unpleasant feeling in (your stomach)
▪ Spicy food upsets my stomach. 3 : to cause (something) to be unable to continue in the expected way
▪ His sudden arrival upset [=disrupted] our plans. 4 : to defeat (someone who was expected to defeat you)
▪ The heavyweight challenger upset the reigning champion in the third round. ▪ She was upset in the primary. 5 : to cause (something) to fall
▪ He accidentally bumped the table and upset a lamp.
▪ That remark you made really upset me. ▪ Don't upset yourself over it. ▪ It upsets him that he can do nothing to help. ▪ A lot of people were upset by the court's decision. ▪ It upsets me to think I might never see him again.
▪ Spicy food upsets my stomach.
▪ His sudden arrival upset [=disrupted] our plans.
▪ The heavyweight challenger upset the reigning champion in the third round. ▪ She was upset in the primary.
▪ He accidentally bumped the table and upset a lamp.
upset the apple cart
informal : to do something that changes or spoils a plan, situation, system, etc.
▪ Let's not upset the apple cart by introducing new rules.
▪ Let's not upset the apple cart by introducing new rules.
— upsetting adjective [more upsetting; most upsetting]
▪ It was a very upsetting situation.
▪ It was a very upsetting situation.
