Oracle Fusion Middleware: OBIEE Unable To Create a User System User Connection BI Server Error - OBIEE'ye bağlanılamaması

We have faced an interesting problem which we were able to solve by updating a parameter

In the picture above there is an error called " Unable to create a user system connection to BI Server"
This tells us that the system user cannot access to the server which is generally corruption of the  system user.

Solution:

We go to the link below  to change the credentials. We click on obiee_domain>security>credentials and then re-enter the password for the system user that we have been using before.  As a result we were able to solve the problem.