Our product doesn't have a defined and written roadmap, which is causing the devteam to receive last-minute requests from some managers.
We will be implementing a roadmap to let all people involved on the product be aware of what's expected of the project, so that they start trading requirements instead of pushing new ones.
How can we avoid CEOs and other stakeholders demanding requirements in a way that constantly breaks the devteam's Scrum routines?
You said:
...causing the devteam to receive last-minute requests from some managers.
Traditional approaches, such as waterfall, assumed that requirements can be written down at the beginning of the project and any changes to that handled through a change management process.
Agile accepted that change is inevitable because of complexities of technology and emerging requirements during the development process. See one of the Agile principles regarding that here:
Welcome changing requirements, even late in development. Agile processes harness change for the customer's competitive advantage.
The Product Owner role was created in Scrum to solve this very problem. Here is the quote from the Scrum Guide:
The Product Owner is one person, not a committee. The Product Owner may represent the desires of a committee in the Product Backlog, but those wanting to change a Product Backlog item’s priority must address the Product Owner.
So to answer your question:
How can we avoid CEOs and other stakeholders demanding requirements in a way that constantly breaks the devteam's Scrum routines?
Assign a Product Owner (PO), if you don't have one already. Empower the PO to receive all such requests for change, discuss with all stakeholders to resolve any conflicts and feed a single priority list to the dev team.
Sounds like you are not actually working within the Scrum framework.
The Product Backlog is an ordered list of everything that is known to be needed in the product. It is the single source of requirements for any changes to be made to the product. The Product Owner is responsible for the Product Backlog, including its content, availability, and ordering.
This is not to say that it is complete or detailed like a traditional project plan.
For the Product Owner to succeed, the entire organization must respect his or her decisions. The Product Owner’s decisions are visible in the content and ordering of the Product Backlog.
This replaces the road map.
No one can force the Development Team to work from a different set of requirements.
The direct answer to your question.
