The Germany international has had what Barcelona described as a "therapeutic procedure" on the patellar tendon of his right knee.
Ter Stegen announced on May 17 that he would miss the Euro 2020 finals in order to make a full recovery.
"I have decided together with the medical team of the club that I will do a complementary intervention on my knee," Ter Stegen said via an Instagram post.
"I'm sad that I will miss Euro 2020 this summer with Germany. For the first time in many years I will be a fan at home supporting my country, I hope we win it!
"After the summer break, when we are back on the pitch I hope to be able to play with fans [in attendance] once again, I miss it!
"Thank you for your support throughout a difficult season and stay healthy!"
Earlier, Barca also announced midfielder Pedri will miss the final match of the season against Eibar on Saturday after being given permission to start his holidays early.
The 18-year-old has played 52 times in all competitions under Ronald Koeman this season, making him the second-youngest in history to reach a half-century of appearances for the club, behind only Bojan Krkic.
Since 2013-14, Arturo Vidal and Ivan Rakitic have been the only two other players to have appeared in 50 games in their first campaign at Barca.
Pedri has played in all 37 of Barca's previous league games this season, starting 28 times.