User is added to Confluence site but is unable to access

Issue Summary

When a new user is added to a Confluence site they are unable to access the site. It can When trying to login they are presented with the errors "Too many redirects" and/or "You're almost there".

Steps to Reproduce

1. Grant Confluence site access to a new user
2. Ask the new user to login
3. Have the new user try to access Confluence
4. The page will try to load and end with the errors "Too many redirects" and "You're almost there"

Expected Results

User should be able to login to Confluence after being added to the site.

Actual Results

User receives the errors "Too many redirects" and "You're almost there" and are not able to login.

The backend logs display an error similar to these:

Caused by: org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "user_mapping_pkey"
Detail: Key (user_key)=(<key>) already exists.

Caused by: org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "cwd_user_name_dir_id"
  Detail: Key (lower_user_name, directory_id)=(<username>) already exists.

Workaround

Reach out to support and we can work with our Identity team to verify if this is the issue being encountered and if so we can correct it on the backend.