That’s according to BBC journalist David Ornstein, who’s revealed a deal failed to materialise because the Gunners could not secure a replacement.
Mustafi, 25, joined Arsenal from La Liga giants Valencia last year and was expected to form a solid partnership with Laurent Koscielny at the back.
However, he struggled to live up to his £35m transfer fee as Arsene Wenger’s side ended the 2016/17 campaign outside of the Champions League qualification places.
Mustafi was heavily linked with an Emirates exit last week - with Inter Milan talked up as his most likely destination.
Ornstein has now confirmed the Germany international was keen to move and that Arsenal were ready to let him leave.
Responding to a Q&A session on Twitter, he said: "Shkodran Mustafi asked to leave, which suited Arsenal because it gave them the chance to replace a player they were disappointed with last season, except they failed to land a replacement."
Arsenal were thought to be interested in getting West Brom star Jonny Evans on-board this summer.
The Baggies were unwilling to sanction a switch though, with Manchester City also in for him.
Away from transfer business, Arsenal will be hoping to get back to winning ways against Bournemouth on Saturday.
They travel to the Vitality Stadium having lost to Liverpool and Stoke immediately before the international break.
