misjudgement
noun /ˌmɪsˈdʒʌdʒmənt/
  /ˌmɪsˈdʒʌdʒmənt/
 (also misjudgment)
 [countable, uncountable]- the act of forming a wrong opinion about somebody/something, especially in a way that makes you deal with them or it unfairly
- The government made a serious misjudgment in its reaction to the crisis.
 
 - the act of estimating something such as time or distance wrongly
- I ran out of wool thanks to a silly misjudgement.