start-stop-daemon does not start because: "process already running"

I have an init script to start qbittorrent-nox on my server. It works fine when I first start the server, but if I shut down the qbittorrent-nox process (service qbittorrent stop) it will not start again (service qbittorrent start), with this error: process already running. I am sure there is no process running, I looked with ps. this is the exact command to start:

start-stop-daemon --start --chdir '/home/testuser' --user 'testuser' --chuid 'testuser:testuser' --startas /usr/bin/env HOME="/home/testuser" /usr/bin/qbittorrent-nox

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