Let's say the following is in the HPEL or SystemOut log when attempting to sign into the WebSphere admin console.

SECJ0118E: Authentication error during authentication for username

For example, in this example, the authentication failed when attempting to sign in as Bugs. 

Bad username / password

The most common cause of this issue that the user simply mistyped their username or password. 

Admin username / password

If you have the administrative username and password for the federated repository, try to sign in using the admin's username and password. Refer to Administrative Security. The administrative passwords will be listed in their encrypted XOR format in the security.xml file. Java can be used to decode the XOR password.

LDAP issue

If the deployment manager is configured to use LDAP to authenticate users, there may be some LDAP issue. Refer to Getting Started with LDAP. To determine if the username exists in LDAP, you can test an LDAP query.

JAAS login module issue

The first time an authentication failure occurs, a First Failure Data Capture (FFDC) log should be created. Let's say the FFDC log has "unable to find LoginModule", something like this. In this scenario, refere to Resolve "unable to find LoginModule".

[6/24/22 4:55:34:603 CDT]     FFDC Exception:javax.security.auth.login.LoginException SourceId:com.ibm.ws.security.auth.JaasLoginHelper.jaas_login ProbeId:503 Reporter:com.ibm.ws.security.auth.JaasLoginHelper@b72b2a19
javax.security.auth.login.LoginException: unable to find LoginModule class: com.example.myLoginModule