The manager for the 'Goonies' star tells TMZ ... an employee at the New Jersey restaurant where Corey was performing live music apparently found the jacket in a bathroom, and locked it in an office.

Remember, Corey hopped on social media Wednesday and franticly posted a thread in ALL CAPS about his coveted jacket being stolen from backstage, and wondered who would have the audacity to take such a beloved item from his wardrobe.

Now it sounds like Corey was seriously jumping the gun with his assumption someone walked off with it, and his manager says they're hoping to pick up the jacket today.

Of course, one reason Corey might have assumed the worst is that his jacket was legitimately stolen once before in L.A., only for it to pop up years later at a Boston flea market and make its way back to Corey.

This time, Corey lost the jacket during his Sunday gig at Homestead Bar & Kitchen in Morristown, NJ. A rep from the bar confirmed the jacket was found in the very bathroom where Corey changed ... so, no big mystery on how it ended up there.

The jacket, which Corey wore in "The 'Burbs" and "Married With Children," holds sentimental value for him ... he says it's a reminder of his late friend, actor Corey Haim.