Problems with the dbase backup

When I go
to delete and recreate the database it always gives me error.

          Now I have deleted the database and created a new

one, but with each backup I get the following error.

          I am attaching the image and configuration

used.

    --snapshot-policy=Required

    --backup-name=Valerio

    --auto-vacuum=true

    --prefix=valerio

    --no-backend-verification=true