Why does my sync with User Sync partially fail?

Problem

Some or all synchronizations with User Sync complete with a status of PARTIALLY_FAILED:

As the status already indicates, some of the users couldn't be created or updated. 
Please find below a list of common causes.

Causes

• User Sync is trying to create a user again which exists already

  • this happens if a user was deleted on the Identity Provider and then created again (i.e. leavers who return to the company)

  • the existing user in Jira, Confluence, etc. has still the old unique user-id from the IdP assigned
    but User Sync only knows the new id and tries to create a new user with the same name, which will fail

  • read here how to fix that https://wiki.resolution.de/doc/usersync/latest/knowledge-base/how-to-fix-the-user-exists-already-error 
    or contact our support and we'll provide you with instructions to fix that https://wiki.resolution.de/go/support
    
    

• "A User with the same username is present in another directory ..." error

  • please read here: https://wiki.resolution.de/doc/usersync/latest/knowledge-base/renaming-user-fails
    
    

• The character limit for usernames in Jira

  • usernames in Jira must not exceed 60 characters due to https://jira.atlassian.com/browse/JRASERVER-42614

  • this usually happens if you sync guest users from Azure without transforming the username

  • read here how to do that: https://wiki.resolution.de/doc/saml-sso/3.6.x/jira/knowledgebase-articles/technical/how-to-transform-azure-ad-guest-usernames
    
    

• "User is not Unique" error message

  • there are currently two users with the same unique Identity provider user ID in the User Sync directory

  • this usually happens, if you change the default primary attribute in the mapping table to something else than its default setting (idp_ID, i.e. azure_ID, okta_ID etc)
    
    

  • please contact our support and we'll provide you with instructions to fix that https://wiki.resolution.de/go/support
    
    

• "ATTR_NAME:NULL must not be null" or "ATTR_EMAIL:NULL must not be null" error

  • the username and/ or email Connector Attribute is empty and User Sync can't create a user without knowing its name or email

  • you need to change the Connector Attributes so that values are provided, using the default mapping values is usually advised

  • if you need to synchronize user names from the onPremisesSamAccountName Connector attribute, syncing users not having that attribute set will cause that error
    
    

• "Fetching groups failed" because of a permanent or temporary network- or database connectivity issues

  • if the instance doesn't have access to the endpoints User Sync is using (https://wiki.resolution.de/doc/usersync/latest/knowledge-base/user-sync-endpoints)
    or if there are database connectivity issues, a sync might also fail partially or completely

  • please contact our support if you don't find the cause yourself and we'll provide you with instructions to fix that https://wiki.resolution.de/go/support