Solution: Turns out the newest version of Flipper-Folly (2.6.9) is causing this issue. Replace that line with: use_flipper!({'Flipper' => '0.92.0', 'Flipper-Folly' => '2.6.7'}) Original answer: Answer on Stack Overflow

Solution: Turns out the newest version of Flipper-Folly (2.6.9) is causing this issue. Replace that line with: use_flipper!({'Flipper' => '0.92.0', 'Flipper-Folly' => '2.6.7'}) Original answer: Answer on Stack Overflow