Keith Urban had to cancel a show suddenly last night due to illness … but there is no way in hell he is missing tonight’s homecoming show, TMZ has learned.

Here’s the deal … Keith’s “High and Alive” tour stop at Bon Secours Wellness Arena in Greenville, South Carolina was scrapped at the last minute yesterday … ’cause his doctor diagnosed him with laryngitis. Naturally, the cancellation made headlines due to the split drama with Nicole Kidman — but this had nothing to do with that.

A source close to Keith tells TMZ … the country music star is on vocal rest all day … right up until he takes the stage Friday evening for his homecoming show at the Bridgestone Arena in Nashville. But it’s totally on — and good thing, too … ’cause it’s damn-near sold out!

And no, Maggie Baugh will not be there … since, as we reported, the rumored romantic interest is not a member of the band, and there are no plans for her to sit in again on tour in the foreseeable future. Worth mentioning, she’s got her own tour going.

Since TMZ broke the news of Keith and Nicole Kidman’s split — and also KU possibly seeing another woman — Maggie was radio silent for a bit … but she’s since seemingly leaned into it to build anticipation for her new album. As far as that album, we’re told Keith had nothing to do with it … and last we checked, had not heard it.