Barbara Walters has reached out to Katy Perry to apologise after “shading” her. The veteran journalist had apparently dissed the “Roar” singer in 2011 after showing up late at their one-on-one interview.

Katy, 28, made it to Barbara’s 10 Most Fascinating People of 2011, which required her to give an interview with the octogenarian.

But 2011 was also the time when her marriage with comic Russell Brand started falling apart so she found it hard to muster enthusiasm for the accolade.

“I shouldn’t have done the interview,” she told Billboard as she graced the magazine’s October issue. “I was playing Madison Square Garden that same night, and I knew that the end of my marriage was coming. I was just exhausted and stressed.

“I’d prepped everyone that I was running late, but Barbara showed up at the original time anyway. When I got there, I apologised immediately, but then she said to me, ‘You know, I’ve only ever waited for one other person this long, and you know who that person was? Judy Garland. You know how she turned out, right?’”

She continued, “I was like, ‘Oh, snap! Yes, b****!’ I think it’s the coolest thing that Barbara Walters shaded me. I just couldn’t tell her as we were sitting down for a mega-interview, ‘Hey, my marriage is falling apart. Give me a break.’”

Katy’s marriage crumbled shortly after that. In December 2011, Russell filed for divorce, citing irreconcilable differences. Neither Katy nor Russell has given any real reason for their separation, though she revealed that he informed her of his decision via text message.

She has also revealed in the Billboard interview that she contemplated committing suicide after her divorce.

Barbara appeared to be clueless of Katy’s real predicament at the time of their interview. So two years after, she has apologised to the chart-topping songstress for contributing to her stress.

She said on the September 30 episode of “The View,” “Katy, if I made you feel at all unhappy during a time when you were obviously unhappy and I didn’t know, I’m sorry,” Barbara said on air. “But you can’t always know.”

Katy’s fourth studio album, “PRISM,” is set for release on October 18. Its lead single, “Roar,” has reached the top of music charts, including Billboard Hot 100 and ARIA.

Barbara Walters’ Katy Perry interview: