The first thing I would want to do is understand why. Did the requirements change? Did we underscope the project? Were there unforeseen technical complexities? Did our capacity or velocity change for any reason? Did other more urgent priorities come up that shifted focus away from this?

Next I would want to understand all of the risks of missing the launch deadline. Are other teams dependent on our work? Are there any external marketing communications tied our to launch? What will be the impact on the rest of our roadmap if we spend another 6 months on this feature set?

Then I would want to quickly switch to problem solving mode. How can we reduce scope or complexity? Are there features that we can scale back to MVP versions, or that we can remove entirely? Are there additional resources we should consider pivoting to get this initiative over the line faster?

I would also communicate out quickly to key stakeholders to provide visibility and transparency to the problems. I would start with a brief communication and then follow up with a more complete action plan as we developed it.

And lastly, after dealing with the immediate upheaval, I would schedule a cross-functional retrospective to understand how we arrived in the situation and what the team could do better in the future to avoid such delays.