The club confirmed on Wednesday that Ter Stegen "still has discomfort" and is therefore unavailable for the match with Valencia at the Benito Villamarin on Saturday.
It means Jasper Cillessen is likely to start, despite Goal understanding that he has agreed to leave the club to join Benfica in the coming transfer window.
[INJURY NEWS] FC Barcelona goalkeeper Marc-André ter Stegen still has discomfort in his right knee and will continue receiving treatment during the coming weeks and, thus, has been ruled out for the Saturday's Copa del Rey final. pic.twitter.com/HpqipPSSN4— FC Barcelona (@FCBarcelona) May 22, 2019
Ter Stegen has played in 49 of Barca's matches this season, including both legs of the Copa semi-final victory over Real Madrid.
La Liga champions Barca are seeking their third trophy of the season, having also won the Supercopa de Espana.
Valencia, meanwhile, have not won any silverware since a 3-1 victory over Getafe in the Copa final of 2008.