Bring Bad News Early, Complete And Without Decoration
How you deliver a problem is read as evidence of how you handle problems generally.
There is a strong instinct to soften bad news, to bundle it with something positive, or to present it alongside a fully formed solution so that the board never sees you without an answer. All three are read accurately for what they are. Softening reads as spin. Bundling reads as management. Arriving with a complete solution to a problem the board is hearing about for the first time reads as a decision already taken and presented for ratification, which is the fastest route to a board that starts checking your work.
The better structure is unadorned. State the problem in a sentence. State the size of it, including the part you cannot yet size. State what caused it as far as you know, without either accepting blame you do not own or distributing it. State what you have already done, what you propose, and what you want from the meeting, which may well be nothing beyond being informed. Then stop talking and let the questions come, including the ones that are unfair.
The thing being demonstrated in that meeting is not competence at fixing the specific problem. It is whether the board can rely on your account of reality. A chief executive who reports a problem accurately and early, including the parts that reflect poorly on their own judgement, buys latitude that is very difficult to buy any other way. A chief executive who is discovered to have known earlier than they said will spend the remainder of their tenure being verified, whatever the merits of everything else they do.