500 internal server error

Error 500 - Internal Server Error at Bonita's first launch

I have installed the Bonita 7.5.2 Tomcat 7.0.76 Bundle and PostgreSQL 9.5, when I run the start-bonita.sh script all is fine and I can access the Tomcat home page through localhost:8080 but when I try to access the Bonita login page at localhost:8080/bonita I get an error 500 entitled "Internal Server Error" by Bonita.
Here it is what I have in the bonita.2018-06-01.log file :

500 Internal Server Error

Hello, I'm having an issue with the Bonita portal.

In the portal, there says that I ran a pool that no longer exists (I deleted the pool).
when I run a different pool, it doesn't show any of the activities in the flow.
I can't run any other process.

In the admin role, I can see there it's a flow from the previous pool I deleted previously.
I can't delete the case, it just shows an error message that says: