emcli test_named_credential failed with ORA-01422

Hello,

I want to understand root of cause of this error -

[oraoem@hostnnnn ~]$ emcli test_named_credential -cred_names=NC_test -target_name=DBNAME.DEV.NET -target_type="oracle_database"
Credential test failed for DBNAME.DEV.NET:oracle_database
Credentials could not be verified. ORA-00604: error occurred at recursive SQL level 1
ORA-01422: exact fetch returns more than requested number of rows
ORA-06512: at line 4


[oraoem@hostnnnn ~]$

I managed to run verb test_named_credential in debug mode but still it is unclear where I have "more than requested number of rows". There is no query mentioned which execution resulted with ORA-1422.