Scrum does not have the role of Project Manager. The work is completed by the three roles in the Scrum Team: Product Owner, Development Team, and Scrum Master123. Project Managers can work on any type of project, while Scrum Masters are exclusive to Scrum projects and Scrum teams2.

A Sprint may be cancelled when the Sprint Goal becomes obsolete. This is because:
* The Sprint Goal is a short-term objective that provides guidance and focus to the Scrum Team throughout the Sprint. It is a flexible and negotiable commitment that can be adjusted as more is learned throughout the Sprint.
* The Sprint is a container for all other Scrum events and activities. It is a time-box of one month or less during which a "Done" Increment is created that meets the Sprint Goal. The Sprint has a consistent duration throughout a development effort and only changes duration between Sprints.
* A Sprint may be cancelled before it is over by the Product Owner if they determine that the Sprint Goal is no longer valid or valuable. This may happen due to various reasons, such as a significant change in the market, technology, business direction, or customer needs.
* A cancelled Sprint should be rare and exceptional. It implies a waste of time and resources that could have been spent on delivering value. It also disrupts the rhythm and flow of the Scrum Team and the stakeholders.
* When a Sprint is cancelled, any completed and "Done" Product Backlog items are reviewed and potentially released. Any incomplete Product Backlog items are re-estimated and put back on the Product Backlog. The Scrum Team then plans for a new Sprint.
Other options, such as when the Developers determine the product plan is infeasible, when it becomes clear that not everything will be finished by the end of the Sprint, or when the sales department has an important new opportunity, are not valid reasons for cancelling a Sprint. They may reflect a misunderstanding of what a Sprint Goal is or how Scrum works.
References:
* [Scrum Guide], page 15, section "Sprint Goal"
* [Scrum Guide], page 9, section "Sprint"
* [Scrum Guide], page 16, section "Cancelling a Sprint"

The two best responses to a Project Manager who has raised concerns about progress and money spent are:
Promote transparency by sharing the Product Backlog and ensuring the Project Manager has access. This helps communicate what is needed to improve the product, what is planned for each Sprint, and what has been done so far. It also helps align expectations and priorities among different stakeholders.
Have a discussion with the Project Manager; share the current impediments and forecast for the Sprint. This helps address any issues or risks that may affect the delivery of value and the achievement of the Sprint Goal. It also helps provide feedback and adaptation based on the empirical evidence and data.
Other options, such as showing the Earned Value Analysis (EVA) report, Scrum does not have Project Managers so disregard their concerns, or sharing the last stakeholder briefing document prepared by the Product Owner, are not the best responses as they do not reflect how to effectively collaborate and communicate with the Project Manager or how to apply the Scrum values and principles.
Reference:
[Scrum Guide], page 11, section "Product Backlog"
[Scrum Guide], page 15, section "Sprint Backlog"
[Scrum Guide], page 10, section "Increment"
[Scrum Guide], page 5, section "Scrum Theory"
[Scrum Guide], page 4, section "The Scrum Team"

Sprint 0 is a term that some organizations use to describe a phase of work before the first official Sprint, where they do some upfront planning, design, architecture, or analysis1. However, this term is not consistent with the Scrum framework, which does not prescribe any pre-Sprint activities or phases2. Scrum starts with a Product Backlog that contains at least one valuable and feasible Product Goal, and enough Product Backlog items to initiate the first Sprint[3][3]. The Product Owner is accountable for maximizing the value of the product and the work of the Developers, and for managing the Product Backlog4. The Product Owner does not have any specific accountability during Sprint 0, because Sprint 0 is not a part of Scrum.
Reference:
1: Sprint Zero: A Good Idea or Not?, Scrum Alliance, accessed on December 16, 2023
2: The Scrum Guide, November 2020, p. 5
[3][3]: The Scrum Guide, November 2020, p. 9
4: The Scrum Guide, November 2020, p. 6