Not only did they have a problem with Messi, now another with Aguero. The player was promised that he would play alongside Messi, but he left. There was a rumour, I'm sure they were mentioned here, they say that because of this situation, he also wants to leave right in this transfer window. From all this follows the conclusion that the Barca will be weak this season, especially if Sergio leaves. And if he doesn't leave, he'll play poorly
If the rumor about Sergio Aguero wanted to leave Barcelona is true then it may be because of the statement made by Di Maria that Aguero wants to kill himself at Barcelona but him leaving the club is impossible because he just signed a two years contract with them this year which the contract started on the 1st of July. How is it possible for him to leave?
I don't know if it's possible to leave Barcelona now, but most likely not. The situation is as funny and incomprehensible as possible. Funny because Sergio came for Messi's sake, and Messi left the club. It seems like lawyers and a football agent are trying to solve the issue of leaving the club due to non-fulfilment of conditions (related to Messi), but even if it works, where will it go? It's unlikely to be accepted back in MC, other top clubs have already bought players for the start of the season. The option is only to wait for next year to make the transition