The following reasons are possible:
1. The attempt was made to grant privileges to a user of a user group.
2. An attempt was made to alter the characteristics of a user who is a member of a user group using an ALTER USER statement.
User characteristics and privileges cannot be altered for members of a user group. This can only be done for the user group itself.
A database administrator can use a QUERY statement issued on the DOMAIN.USERS system table to find out which user group the relevant user belongs to. Other users only see the users and user groups that belong to the same database administrator as they do.
1. Grant the appropriate privileges to the user group that the user belongs to.
2. Replace the ALTER USER with ALTER USERGROUP statement.