Torを起動しようとすると以下のエラーが表示されます。

example@example:~$ tor
Aug 29 12:53:45.307 [notice] Tor 0.3.2.10 (git-0edaa32732ec8930) running on Linux with Libevent 2.1.8-stable, OpenSSL 1.1.1, Zlib 1.2.11, Liblzma 5.2.2, and Libzstd 1.3.3.
Aug 29 12:53:45.307 [notice] Tor can't help you if you use it wrong! Learn how to be safe at https://www.torproject.org/download/download#warning
Aug 29 12:53:45.307 [notice] Read configuration file "/etc/tor/torrc".
Aug 29 12:53:45.309 [notice] Scheduler type KIST has been enabled.
Aug 29 12:53:45.309 [notice] Opening Socks listener on 127.0.0.1:9050
Aug 29 12:53:45.309 [warn] Could not bind to 127.0.0.1:9050: Address already in use. Is Tor already running?
Aug 29 12:53:45.309 [warn] Failed to parse/validate config: Failed to bind one of the listener ports.
Aug 29 12:53:45.309 [err] Reading config failed--see warnings above.

エラーのうち、以下のメッセージから9050portが使われてるかを確認しました。

Could not bind to 127.0.0.1:9050: Address already in use. Is Tor already running?　

確認結果

example@example:~$ sudo lsof -i:9050
COMMAND  PID       USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
tor     4031 debian-tor    8u  IPv4  57166      0t0  TCP localhost:9050 (LISTEN)

試しにkillしてからtorを起動すると以下のような結果になりますが、Torの画面が表示されないです。再起動しましたが結果は同じでした。
原因は一体何でしょうか？

example@example:~$ sudo kill 4031
example@example:~$ tor
Aug 29 13:01:46.402 [notice] Tor 0.3.2.10 (git-0edaa32732ec8930) running on Linux with Libevent 2.1.8-stable, OpenSSL 1.1.1, Zlib 1.2.11, Liblzma 5.2.2, and Libzstd 1.3.3.
Aug 29 13:01:46.402 [notice] Tor can't help you if you use it wrong! Learn how to be safe at https://www.torproject.org/download/download#warning
Aug 29 13:01:46.402 [notice] Read configuration file "/etc/tor/torrc".
Aug 29 13:01:46.404 [notice] Scheduler type KIST has been enabled.
Aug 29 13:01:46.404 [notice] Opening Socks listener on 127.0.0.1:9050
Aug 29 13:01:46.000 [notice] Parsing GEOIP IPv4 file /usr/share/tor/geoip.
Aug 29 13:01:46.000 [notice] Parsing GEOIP IPv6 file /usr/share/tor/geoip6.
Aug 29 13:01:46.000 [notice] Bootstrapped 0%: Starting
Aug 29 13:01:46.000 [notice] Starting with guard context "default"
Aug 29 13:01:46.000 [notice] Bootstrapped 80%: Connecting to the Tor network
Aug 29 13:03:59.000 [notice] Bootstrapped 85%: Finishing handshake with first hop
Aug 29 13:04:00.000 [notice] Bootstrapped 90%: Establishing a Tor circuit
Aug 29 13:04:01.000 [notice] Tor has successfully opened a circuit. Looks like client functionality is working.
Aug 29 13:04:01.000 [notice] Bootstrapped 100%: Done