Barça has four goalkeepers on its current roster. The coaching staff's idea was to define clear roles before the start of the league. However, plans can change at any moment.
Joan García was signed for €25 million as the big name for the goal. His potential, youth, and current level convinced the sporting department. In principle, he was supposed to be the starter from matchday one.

Wojciech Szczesny, meanwhile, has recently renewed his contract. He has done so by accepting a secondary role, but expecting minutes in the Cup and in some rotation matches.
Joan García and Szczesny, main goalkeepers, but their registration is not guaranteed
Behind them are two names with more history in the locker room: Iñaki Peña and Ter Stegen. Both remain linked, although Hansi Flick doesn't count on them. Even so, their situation has not been solved.
The big surprise has come this week ahead of the start of La Liga. Neither of the two main goalkeepers has been officially registered in the competition. This greatly complicates Flick's plans.
Under normal conditions, the coach would have chosen Joan García without hesitation. But since he is not registered, Barça faces a possible administrative problem that could change the starting line-up.
Ter Stegen doesn't want to sign the medical consent and La Liga can't approve his absence
The option to activate Ter Stegen's medical leave is on the table. The German is still injured and has not been cleared. However, he refuses to sign the consent that would allow other teammates to be registered.

This leaves the sporting management with no room for maneuver. Without that document, La Liga can't approve his temporary replacement. Flick and his team have found themselves in a completely unexpected situation.
Meanwhile, the days go by and the first league match is just around the corner. There is only one name officially registered as a goalkeeper.
Iñaki Peña, from discarded to starter on matchday one: the only goalkeeper available for Flick
Although he seemed out of the plans, Iñaki Peña is now the only goalkeeper who can legally play. He has a contract, an active registration, and is not injured. Therefore, he could be the starter against Mallorca.

The coaching staff are already preparing for that scenario. Peña, who had been relegated by Joan García and Szczesny, could have an unexpected opportunity. This is further proof of how unpredictable soccer can be.
As soon as the paperwork is in order, Flick will be able to count on all his players. Until that happens, everything points to Iñaki Peña being the goalkeeper. The league debut will have a surprise between the posts.