In an announcement via Twitter, the convention put the blame squarely on the NFL, saying the league's "blatant and continued interference has fractured beyond recovery our capacity to deliver the unique opportunities the NFFC had intended to provide."
Last year's convention, which was set for Las Vegas, was delayed after the NFL let players know of the league's policy against appearances in a casino.
This year's convention was set for July 15-17 in Pasadena, California, with players representing every team due to be in attendance to meet with fans and sign autographs while fantasy football experts doled out advice.
"It's been an uphill battle, considering we are fighting the 800-pound gorilla," NFFC executive director Andy Alberth said.
In April, the NFFC was granted a temporary restraining order preventing the NFL from contacting sponsors of the event. According to the request, the NFFC felt the league was "harassing" its sponsors and clients in issuing subpoenas seeking information about each company's role in the 2015 convention. That order expired in May.
The NFFC remains in litigation against the NFL. In February, a Dallas judge threw out a tortious interference claim brought by The Fan Expo, LLC, that led to the cancellation in 2015. An appeal has been filed, and there are two other claims, including breach of contract. One of The Fan Expo's attorney's, Michael Hurst, said the hope is to depose NFL commissioner Roger Goodell.
A spokesman for the NFL said the league would not comment on the convention.
In its Twitter announcement Tuesday, the NFFC said it was "not going away" and that a new date for the convention would be determined.