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Concerned fans took to the internet when Howard Stern unexpectedly canceled his radio show to take a “personal day” Wednesday.

The SiriusXM host, who fans claim has never taken an unexpected day off, mysteriously went off the air this week without explanation.

“I have listened to the #HowardStern show since the 80s… NEVER canceled a show before! I am very concerned about the reason,” one Twitter user wrote. Another fan commented, “Peace and love to my hero @HowardStern, who has missed a live show for the first time ever this morning. I hope everything is ok.”

Stern’s absence, which was announced as a “personal day” on air Wednesday, sparked multiple Reddit threads and conspiracy theories about what could have caused the unexpected cancellation.

The rumors ranged from marital troubles with wife Beth Stern to the passing of one of his parents to legal issues with Sirius after he was sued for airing a woman’s confidential call with the IRS. Many expressed concerns about 63-year-old Stern’s health.

One Reddit user pointed out, “Just this year Howard said the only way he’d cancel a show is if a parent died,” but it was also noted by someone else that Stern poked fun at his 93-year-old father on Monday’s show and wouldn’t do that if “he was on his deathbed.”

Multiple fans also mentioned that Stern was in a sour mood on Monday’s show, suggesting the two things could be related.

He is expected to return to the airwaves this Monday.

“The Howard Stern Show” has yet to make an announcement about the reasoning behind Stern’s absence and did not respond to our request for comment.