The following snippet can be seen in server.log file while the same user can still log in to the Spotfire server.
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dbLogin.dbLoginModule:Failed to authenticate user 'xxxxx'
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Failed to authenticate user 'xxxxx' message in server logs but users can still log in

All supported environments

This happens if LDAP authentication is enabled on the Spotfire server. By default, Spotfire first goes to the Spotfire database to look for the user information. If it does not find the user information there and the authentication against the Spotfire database fails, it then goes to the LDAP Active directory to check for the user information there. If Spotfire finds the user information there, it successfully authenticates the user against the Active directory and the user can log in successfully. The failed authentication message is not an error but just an indication that Spotfire could not authenticate the user against the Spotfire database. Right after the failed authentication message, following message for successful authentication will be seen.
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jaas.ldap.LDAPLoginModule: Successfully authenticated user 'xxxxx'
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This means Spotfire could successfully authenticate the user against the LDAP Active Directory.

Note: The successful authentication message is only seen if the server logs are in debug mode. At info level, this message is not recorded.