Comment by pyfon

The manager needs to judge if it is a one off oversight, a skill issue or an attitude issue.

I think it is better to talk to everyone civilly and respectfully regardless and then use fair processes to deal with these issues.

Broadly you have 2 possible issues:

1. People make mistakes and you need processes like code reviews and tests etc. to catch them. No one does 100% perfection. Avoid blame.

2. Someone is not performing well enough.

You deal with 1 as a team through continuous improvement. And 2 is usually manager and team member through feedback and perhaps performance improvements. It should be utterly respectful at all stages.