Barcelona had previously signed Dani Olmo from RB Leipzig for a reported €55 million, but the move caused significant problems for the club. They struggled to register Olmo due to their financial constraints, and it wasn't until Andreas Christensen's injury that they were able to temporarily register him.

La Liga later revoked Olmo's registration, and Barcelona's appeal was rejected. Despite this, they continued to pursue Williams, hoping to add one of Europe's best young attacking talents to their squad.

However, it was the lack of a written guarantee that Williams would be registered by Barcelona without issue that ultimately led to the deal falling through. Williams wanted assurances that he would be registered, but Barcelona's sporting director Deco was unwilling to provide them.

Instead, Deco promised Williams' representatives that they would register him by the end of the summer, but this was not enough to convince Williams to join the club. In the end, Williams signed a new deal with Athletic, keeping him at the club until 2035 and increasing his release clause to a reported €87 million.

Barcelona's failure to sign Williams has left them to look for new targets, with Luis Diaz and Marcus Rashford being discussed internally by the club. However, any potential deal would be tricky, given Williams' high wage demands and new release clause.

The likes of Arsenal, Bayern Munich, and Chelsea have also been linked with a move for Williams in the past, but any potential deal would be complex due to his new contract and high demands.

Despite this setback, Barcelona will continue to pursue their transfer targets, but it remains to be seen whether they will be able to secure the signings they desire.

The club's financial situation remains a concern, and it will be interesting to see how they navigate the transfer market in the coming months.

For now, Williams will remain at Athletic, and Barcelona will have to look elsewhere for their next signing.