ORA-28000: the account is locked in Active Data Guard

OS VERSION:SUSE Linux Enterprise Server 12 SP2

DB VERSION:12.1.0.2.0

An error is reported when I execute the following command：

Connected to:

Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production

With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,

Advanced Analytics and Real Application Testing options

SQL> select database_role from v$database;  

DATABASE_ROLE

----------------

PHYSICAL STANDBY

SQL> alter user aiuap account unlock;

alter user aiuap account unlock

*

ERROR at line 1:

ORA-00604: error occurred at recursive SQL level 1

ORA-16000: database or pluggable database open for read-only access

ORA-06512: at line 1309

ORA-16000: database or pluggable database open for read-only access