OK. Then the next thing you can do is hide slides and then republish to try and find whether something in or on a slide is causing the issue. Hide all slides in the first half of the project and then republish. If it still doesn't work, hide the final half of the project instead. If that works, use a process of elimination to progressively narrow down the location of the offending slide.
If none of the slides turn out to be a problem, the issue may be in your variables or advanced actions. Take a copy of your project and start deleting actions and variables to try and find the one that is causing the issue.