Error in data foundation: "Could not register operator to the buffer manager: Too many executable operators (5), max is 5"

Hi,

I am trying to view table values from 2 tables in the data foundation, but I am getting the error:

[Data Federator Driver] [Server] Could not register operator to the buffer manager: Too many executable operators (5), max is 5

I could not find anything regarding this message. Did anyone experienced this situation? Do you have any suggestions?

Lavinia