Tony Gilroy has carved out a successful career over three decades in Hollywood with credits including the four films in the Jason Bourne movie franchise and the 2007 Oscar-winner "Michael Clayton."

However, the veteran writer-director has had his share of challenges in his field as he told Montclair State University students on Monday about his experience working on the 2016 film "Rogue One: A Star Wars Story."

The movie earned over $1 billion worldwide at the box office, but was reportedly a difficult production that led to Gilroy being brought in to rewrite the script and oversee some reshooting.

When pressed by Susan Skoog, director of programming at The Film Institute at Montclair State, about "what went wrong" with Rogue One, Gilroy hesitated to answer to avoid getting into trouble with the producers of the movie, but then responded that it was a matter of "purity" when telling the story.

"When things pass through many hands and there's a great deal of confusion ... and there's all kinds of accessories and jewelries and bootstraps and zippers, and all the rest of the stuff. The purity for the characters, if it's not there to begin with, it just deteriorates and just turns into an absolute mush," Gilroy said.

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Gilroy appeared as part of MSU's Dialogue with a Screenwriter series, co-presented with the Writers Guild of America, East.

The 90-minute session was interspersed with clips from his films and included a Q&A with students.

He addressed a variety of topics from how he starts writing a script to what it takes to become an accomplished scribe like himself.

"Just write like hell, just keep writing," Gilroy advised.

He then said that a fledgling writer shouldn't have just one screenplay done to present to producers, but "your 19th script" to show a body of work and a dedication to the craft.

Gilroy also let the audience know that they should not take rejection of their work personally as he had to learn when starting out.

"People are not against you, I always thought everybody was against me," Gilroy said. "In truth, that's not the case. You find out later on when you are inside the sort of citadel, it's like you really want to find people."

He said, "Nothing is as jazzy as finding someone who's really good."

Email: kaulessar@northjersey.com