Nothing to do: it does not work

CUPSD is running, as expected. But trying http://localhost:631 gives the following error:
Code:
internal error - server connection terminated
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 Description: internal error - server connection terminated 
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Moreover, there must be something else wrong, because if I try to launch any Epson tool (like the head cleaning job, the ink level meter, and so on) I get the following error message:
Code:
The executable escputil was not found in your PATH.
Make sure that gimp-print is correctly installed and that escputil is in your PATH
By the way, while reinstalling for the n-th time the printer, I tried out all of the available drivers. No one works, but one of them, only one, if I press the "Test driver" button, makes the printer to load and immediately eject a sheet. The printer still does not attempt to print anything.

And that's all, because if I choose the "Test printer" command, even with this driver, no nothing happens.

Any other ideas?