Hong Kong activist leader Joshua Wong is released Monday, September 9, the next day after he was arrested at the airport due to an error in his bail certificate.

The 22-year-old was detained Sunday at the Hong Kong International airport for “breaching bail conditions” after returning from Taiwan and taking another overseas trip to Germany.

A Hong Kong court on Monday states the arrest is a mistake because Wong’s bail conditions allow him to take overseas trips that are prearranged before his arrest.

Wong, who was one of the pro-democracy leaders of the 2014 Umbrella movement, is seen rushing out of the court building.

Speaking first in Cantonese, Wong says, “Everyone including me, my lawyer, and even the government's lawyer did not expect this to happen."

He tells reporters that the recent “indiscriminate arrests” and confiscation of passports of the majority of people detained “only leads to more conflicts.”

The young activist thanks the lawyers for their help.

“The overnight detention is wholly unacceptable and unreasonable,” tweets Wong, who anticipates “Uphill battles ahead,” calling his overnight detention as “somewhat absurd encounter.”

Meanwhile, thousands of high school and university students form human chains outside schools across Hong Kong on Monday to show their solidarity for change, following the weekend clashes.