Symptoms

When changing the site homepage using the directions from Configuring the Site Home Page, the error below pops up

"The SPACENAME space must be accessible to the confluence-users group (or anonymous view permissions must be granted) in order to be set as the Site Homepage."

Diagnosis

The error message above pops up because the space does not have the group "confluence-users", or anonymous, in the view permission

As specified in Configuring the Site Home Page 

Which means the space that would be set as the Site Home Page should either have an anonymous access, or has "confluence-users" group as one of the groups that has a "view" permission

Cause

This behavior is set by design. A few users, more prominent in Confluence OnDemand are affected by this and being tracked by the bug reports below:

1. CONF-27791 - Getting issue details... STATUS  and 
2. CONF-26302 - Getting issue details... STATUS

Which both are closed as "won't fix" as it is minor issue. 

Workaround:

Manually create a group called "confluence-users" and grant it View permission for that space. There doesn't need to be anyone actually in the group, it just needs to be granted View permission.

1. If there is no "confluence-users" group in Confluence present, manually create the group in Groups page from Confluence Admin (See: Confluence Groups).
2. Add "confluence-users" as one of the group with 'view' ability in the space in mention
   • Go to this space > Space Tools > Permissions > under 'Groups', add 'confluence-users' > Click 'add' > Give this group 'view' permission
   • 
3. Try to set this space as the dashboard again