User profile information not accessible, asking you to log in (disabled People Directory)

Problem

When accessing user profiles in any way, e.g.

then, depending on your Confluence and Linchpin version, either an info panel with the following message is displayed:

The content of this macro can only be viewed by users who have logged in. Please log in to view this content.

or one of the rendering exceptions listed below occurs:

Linchpin Intranet Suite, Linchpin Essentials or Linchpin User Profiles are installed and active

Navigate to the Confluence administration section Administration > System Information (URL fragment: /admin/systeminfo.action)
Check the list of CATALINA_OPTS to see if one or more of the following properties is set to true:
- ```
-Dconfluence.disable.peopledirectory.anonymous
```
- ```
-Dconfluence.disable.peopledirectory.all
```

Your Confluence is most likely configured to prevent users from accessing the People Directory through the UI.

Background information on why this might be the case can be found in Atlassian's Knowledge Base article about Hiding the People Directory.

Depending on the desired system configuration, ...

if you would like users to be able to access profile information of other users, including the people directory:
→ unset the system properties and restart your Confluence service
if you would like to continue blocking (certain or all) users from accessing the people directory:
→ in this case, our app Space Privacy might be worth looking into! It allows collaborating with external users without exposing all your Confluence user details to them.
if you're not sure why the system properties are set:
→ try asking the people in charge of managing your intranet whether this setting is/was intentional