BMXAA4214E while trying to update Supervisor field on Person records

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Problem:
Error in People application while trying to update Supervisor field on Person records.

Symptom:
The error is thrown while trying to save the record:

BMXAA4214E - An unknown error has occurred.
Please contact your system administrator for assistance.
Gather the logs from the <HOME> directory and determine where and why the error is thrown.

Resolving the problem:

1. Run the query below against the database to try to find a  Person being the Supervisor of itself:
SELECT PERSONID, SUPERVISOR FROM PERSON WHERE PERSONID = SUPERVISOR;

2. Run the query below against the database to try to find a Person being a Supervisor of a Person who is the Supervisor of the original Person.
SELECT PERSONID, SUPERVISOR FROM PERSON;
The idea is: take the Person record with the issue and check who his/her Supervisor is. Then check who the Supervisor of that Supervisor is. Keep doing this until to reach the top. Ensure that a Supervisor doesn't loop back to a Person record.

If the problem still persists even after trying these suggestions, please contact IBM Maximo Support.