What is required for a Jira software user to share a Kanban and/or Scrum board with other users?

[Vindicia IT]

I have a user who is a Jira software user and has been granted Sprint Manager permission, but when he creates a new Kanban / Scrum board, no one else is able to see it. We can't figure out how to share access to other Jira software users. I have Jira administrator permission but I can't see the boards either, due to "Error: The requested board cannot be viewed because it either does not exist or you do not have permission to view it."

[Jan]

The filter used for the board needs to be shared.  (Go to Board Configuration, General, locate the filter and share that filter)

[Jack Brickey]

The owner of the board need to go to Board settings and share the board with all logged in users or groups.