David Harbour says that he had panic attacks while making 'Stranger Things' season one and feared that its release would be 'humiliating'

• David Harbour said that he thought "Stranger Things" would be "terrible" and "humiliating."
• The actor said that he found the pilot script compelling, but worried about the show failing.

David Harbour worried that the release of "Stranger Things" would be "humiliating," and feared that the show wouldn't succeed despite his early belief in the project.

In an interview with Yahoo! Entertainment, Harbour said that his character on the 1980s-era drama, Jim Hopper, immediately felt compelling. But while the pilot script was "probably the best" that he'd ever read, he said he thought that there likely wouldn't be interest in the series.

His worry intensified when he showed up to film the first season in Atlanta, GA.

"In the middle of this process, I had nights where I would just be in a panic attack thinking 'This is terrible,'" Harbour told Yahoo! Entertainment. "Like, 'This is a terrible show. I'm terrible in it. And it's just gonna be humiliating.'"

The actor made similar comments on the BBC's "The One Show" in July, saying that he thought the show was going to be a "disaster."

"Stranger Things," of course, proved to be a massive success. Six years after its 2016 premiere, the show is one of Netflix's biggest titles: set to conclude in its fifth and final season, the show will eventually be followed by a spin-off series at Netflix produced by "Stranger Things" showrunners Matt and Ross Duffer's production company, Upside Down Pictures.

Harbour told Yahoo! Entertainment that prior to the series' launch in 2016, he didn't feel like Netflix was heavily advertising the show after a friend told him that he hadn't seen a single "Stranger Things" advertisement in New York City.

That led Harbour to believe that Netflix hated the series, and that it was going to be "another failure in a long string of failures" in his career.

"That's why it was all the more satisfying, cause instead of this big hype thing, it felt real grassroots," Harbour said. "Like people discovered this little show on Netflix and it ballooned into this zeitgeist, which it is now."