Submitted by: @pavel-zotov

SQL> create user u01; ------------------------------------------------- [ 1 ]
Statement failed, SQLSTATE = 42000
Dynamic SQL Error
-SQL error code = -104
-Unexpected end of command - line 1, column 13

SQL> create or alter user u01; --------------------------------------- [ 2 ]
Statement failed, SQLSTATE = 42000
unsuccessful metadata update
-ALTER USER U01 failed
-ALTER USER requires at least one clause to be specified

SQL> create or alter user u01 firstname 'john'; ---------------------- [ 3 ]
Statement failed, SQLSTATE = 23000
add record error
-validation error for column "PLG$USERS"."PLG$PASSWD", value "*** null ***"

SQL> create user u01 revoke admin role; ------------------------- [ 4 ]
Statement failed, SQLSTATE = 42000
Dynamic SQL Error
-SQL error code = -104
-Token unknown - line 1, column 17
-revoke

SQL> create or alter user u01 revoke admin role; ------------------------ [ 5 ]
Statement failed, SQLSTATE = 23000
add record error
-validation error for column "PLG$USERS"."PLG$PASSWD", value "*** null ***" // same for 'grant admin role;'

All five messages appear due to missing 'password' clause. Messages in [3] and [5] looks more informative than other, but it would be nice if text will be more appropriate for end-user, like: 'missing password clause' or so.