The correct answer to this open question is the following.
As this is a difficult situation because your employees are expecting the bonus, as happened in previous years, you have to be delicate in the way yo explain to them the reason why there would be no bonus this year.
If you just write what is written in the question. You are not sensitive. That is why you should write something like this:
Dear members of our team,
As you know, this year has presented us with major challenges we have never seen before. We are living difficult times and our company is making every effort to overcome adversity. The results were not good as in previous years and we are not in the position to give the annual bonus. We feel terribly sorry because we know how much the bonus means to all of you. This is a tough decision, but the one we had to make in order to keep our jobs safe. We ask you for your understanding and support and invite all of you to keep on doing the great work you do to change the situation and make this next year, a profitable one.
