Can you share a time when you faced failure in a project and what lessons did you learn from the experience?

We worked on a project and got stuck on a problem where the common solution does not satisfy our goals of minimizing the risk of customer impact and minimizing the workloads on over 30 partner teams.My task is to get the team unblocked and find the best solution

• I drafted our detailed requirements and constraints with diagrams, and shared with the partner team owing to the key component we don’t have enough knowledge on, and explained our situation and why the common solutions would not be the best for us.
• I facilitated our team brainstorm sessions to explore all possible directions we could explore with the limited knowledge we have, and we got a few ideas.
• I followed up with the core team on the requirements and our probing questions and the feasibility of the ideas from team brainstorm
• After a few interactions of exchanging information and ideas, both side were able to find a couple of solutions to the problem, and with tradeoff discussion, we narrowed it down to one solution which minimizes operation and coordination cost with manageable risk.
• With core team’s support, we were able to implement and verify the solution successfully and get unblocked on the project
•  the project is rolling out to production with peace in mind that the risk of customer impact is very low
• Learning: detailed description on the requirements.  Identify dependencies in detail and ahead of time, have 1:1 discussion with pertner team

WE made a bad build vs buy decision, we built an entire tool to store our metric definitions and build a change management system around it , a UI around it to allow users to change metric definition, other features were built around security but the problem this is not our core competency and management of this service became head ache, we did not have dedicated back end engineers and the project is in KTLO mode for a long time , things slowly started breaking and  no engineer was there to maintain it...finally we decommissioned it and bough a plug in tool called DRM. Lesson learned , identity your core competency of the team and if this project fits in your vision, this is not a DE project and should never have been built by us