From yesterday's Corriere della Sera, Milan's daily newspaper: "Piermarini: contestato Barenboim, Applausi (e "buu") a Domingo".
"Piermarini [La Scala]: Contested Barenboim, Applause (and boos) at Domingo"
Some boos welcomed Placido Domingo, yesterday night at the premiere of Verdi's Simon Boccanegra: at his entrance to the stage and at the end of the third act. At the end of the opera, however, the tenor, here in the role of the baritone, had returned to the stage only 45 days after an operation on his colon, and was welcomed with applause that lasted around 14 minutes and some isolated boos. Many of the protesters there instead reserved most of their booing for the conductor, Daniel Barenboim, and also some for the director, Federico Tiezzi, not only at the end of the performance, but also at the entrance after the intermission, where there was an exchange of insults (culminating in an unusually heard "Vaff..." between the detractors and an advocate from the audience.
All translations from OC tia.