Also known as: Glass Case Plan, Detailitis Plan.
In many organizations, detailed planning is assumed to be free of downside. That assumption holds for manufacturing. It does not hold for software, where the work is full of unknowns that a plan can't see coming. Death by Planning happens when a plan for a software project gets taken more seriously than the software itself.
Projects fail from over-planning as often as under-planning. Either way, the plan becomes the deliverable people actually manage to, while the software itself drifts.
Rational Planning: replan from facts as the project produces them, rather than defending a document written before anyone knew what the real problems were. A plan is a forecast, not a commitment device, and it should update as often as the facts do.