A Wetherspoons pub which closed after several staff fell ill was shut because of an outbreak of winter vomiting bug norovirus.
The chain was now confirmed the cause of the illness at the Winter Gardens in Harrogate town centre.
The pub had previously announced it would be closed until Friday for deep cleaning after staff fell sick with a mystery bug.
The cause of the infection isn't known - although Wetherspoons have assured customers that it is not food-related.
Wetherspoons spokesman Eddie Gershon said: "Staff members reported symptoms that are consistent with norovirus, which is sometimes referred to as the winter vomiting bug.
"The cause of the infection is not yet known but there is no indication that it is food related. The closure of the pub and thorough clean down is a precautionary measure as advised by local authorities and Public Health England."
The historic pub was once part of the town's Royal Baths spa complex. The Winter Gardens area was an indoor palm court where orchestras would play in the 1920s.