A project is having issues because uncertain events have occurred that were not tracked and planned for. This could have been avoided by using:

A risk register is a document that tracks identified risks, their potential impact, likelihood, and planned mitigation or contingency responses for uncertain events that may affect the project. By using a risk register, these uncertain events would have been identified, tracked, and planned for, allowing the team to address them proactively.

Change management controls modifications to the project, not the identification and planning for uncertain future events.

An issues log tracks problems that have already materialized, it does not proactively track uncertain future events.

A communication plan focuses on information dissemination, not on identifying and planning for potential uncertain future events.