When Does the PMP Exam Change?
PMP exam changes happen regularly. There probably was a change to the exam just yesterday. This is because PMI develops and releases new exam questions on an ongoing basis. Adding new questions can be viewed as a 'minor' update. But PMI also has 'major' updates.
One reason for such a major update is the actualization of the PMP Exam Content Outline which the PMP exam is based on. The PMPECO is aligned to the current project management reality about every 6 years. And usually, 6 months after the release of a new PMPECO the PMP Exam does change to align with that new PMPECO.
Another reason for such a major update of the Exam can be the update to the PMBoK Guide.
As project management and the PMPECO evolves, so do PMI's standards.
The PMBOK® Guide is updated like clockwork -- every four years. And so the PMP exam questions are changed to reflect the most recent version of the PMBOK® Guide.
As an example: The PMBOK® Guide 6th edition was released in September 2017 and the PMP exam was updated to reflect this new standard on the 21st of March, 2018.