“Sam and Cat” is the hottest live-action series entry on Nickelodeon in the past few years, but the pressure of a 40-episode production schedule seems to be wearing on its stars, Jenette McCurdy and Ariana Grande.

The series has gone on hiatus early, before finishing its entire first-season production order, because of what sources described as sniping behind the scenes between McCurdy and Grande, both in their early 20s, and other tensions on the set.

Sources close to the production chalk it up to a grueling work schedule for the young actors. The tensions on the set spilled over into social media this past weekend and were apparent when McCurdy did not attend Nickelodeon’s Kids Choice Awards event this past Sunday where “Sam and Cat” creator/exec producer Dan Schneider was honored with a life achievement kudo.

Sources said the hope is that some downtime for McCurdy and Grande will allow the situation to simmer down, and if so they might reconvene for the remaining episodes. The show is believed to have completed lensed at least 32 episodes.

“Sam and Cat” premiered last June with a 20-episode order. Nickelodeon quickly ordered another 20 after the series that brought together characters from two past Nick series, “iCarly” and “Victorious,” emerged as a success for the kidvid cabler that had been in a ratings slump until last year.

Sources sought to downplay speculation that the off-camera problems might torpedo the show for good. Schneider and his fellow showrunner Warren Bell had been pushing Nickelodeon to take a mid-cycle break to give the girls a rest.

Sources acknowledge that one source of tension is likely to be the fact that Grande is garnering a larger sure of the spotlight outside of the show as her musical career blossoms.

A spokeswoman for Nick would only say that the show would take a “much-needed rest” next week. Deadline was the first to report on the “Sam and Cat” production issues.

“We are wrapping up what was an unusually long production cycle of ‘Sam & Cat,’ and everyone is understandably tired,” she said.