Made a mistake, now what?
The work that we deliver is our work, as professionals we should refrain from making excuses and take responsibility.
Sometimes working in a team it may not be clear who was the one who actually made the mistake, but I find that usually it's not about who's fault it is as we should take collective responsibility to find the solution to fix the mistake. A blame culture rarely helps anyone.
Communicate the problem as early as possible
The moment we know that a story won't be completed on time. We should notify relavant stakeholders. The early they know, the more time they have to make an informed decision on what to do about it. This relates to estimation, sometimes we don't know exactly when a feature will be completed so we make an educated guess, that's all an estimation is however we must communicate when we can't meet the estimated deadline.
Offer a solution
People prefer solutions than excuses. If not a solution, an alternative that would allow the project to continue moving forward.
Learn from the mistakes made
Last but not least, we must learn from our mistakes so we don't make it again. A craftperson is always in the state of self improving. We will never be perfect but we should always strive to be better than yesterday.
As I'm going through my apprenticeship, I think this may be the most important. I'm always string to soak as much information as possible, to lessen my mistakes, to be better and better. Always giving maximum effort to prevent making the same mistake again.