Reds boss Mark Robins brought back Andy Gray and Bobby Hassell while Liam Dickinson, Nathan Doyle and Jacob Butterfield missed out following the shock cup exit at the hands of Rochdale.
There was a shock place in the starting XI for defender Stephen Foster, who defied doctors' advice to line up for the Reds despite suffering concussion on Tuesday night and Diego Arismendi made his Oakwell debut in midfield.
The Tykes, who had not won their first home league match of the season since beating Swindon 2-0 in August 2005, were without a win in 11 Championship games, their last victory coming at home to Nottingham Forest on March 16.
However, McCarthy's blunder proved enough to ensure the Reds got up and running on this occasion.
Robins said: "I thought we were decent, especially after the week we've had. I love watching them in training, I think their movement is good and when they settle down and really start to believe they'll be a really good side.
"It's important to get a win because you've got all the outside pressures which are heaped upon you.
"We're trying to make a big, big change from what was here before and I think you could see signs of it, but it's not what they're capable of producing.
"We kept Palace very quiet and restricted them to nothing.
"The only disappointing thing was that we had to rely on an own goal."
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