Error Rendering Page Property Macro "com.k15t.scroll.platform.model.SpaceRoles"

Symptoms

An error message is rendered instead of the Page Property macro content: "Error: com.k15t.scroll.platform.model.SpaceRoles cannot be cast to com.k15t.scroll.platform.model.SpaceRoles."

Cause

Plugins cache is corrupted.

Solution

1. Stop Confluence,
2. Clear plugins cache:  https://confluence.atlassian.com/confkb/how-to-clear-confluence-plugins-cache-297664846.html
3. Start Confluence.