I assure you this won't happen again.

Meaning

Giving a strong guarantee that a similar problem will be avoided.

Examples

• John: 'This is the second time this has occurred.'<br>
• Alice: '<b>I assure you this won't happen again</b>, John. We have implemented new procedures to prevent it.'
• John: '<b>I assure you this won't happen again</b>, Alice. We are taking disciplinary action to address the issue.'
• Alice: 'This level of negligence is unacceptable.'<br>