The 29-year-old striker is the subject of interest from Toluca in his native Mexico.
Herrera joined during last year’s summer transfer window for over £1million but failed to impress during his 12 months in the first-team.
He made 24 appearances in total, though only two were from the starting XI, and scored two goals.
This latest news comes just a day after the Mexican international posted a defiant message on his Instagram page, writing: “Always remember that your present situation is not your final destination. The best is yet to come. #keepmovingforward.”