Error: Unable to write pid file Mosquitto v2.0.3

since I updated Mosquitto v2.0.3 on Ubuntu 16.04 the users can't connect to the broker.

When I tried to run with /usr/sbin/mosquitto -c /etc/mosquitto/mosquitto.conf it threw the following message. 2020-12-22|12:37:02: Error: Unable to write pid file.

I saw some people had the same problem, so I added pid_file /var/run/mosquitto/mosquitto.pid in mosquitto config but the problem did no go away.

I have this in /lib/systemd/system/mosquitto.service:

[Unit]
Description=Mosquitto MQTT Broker
Documentation=man:mosquitto.conf(5) man:mosquitto(8)
After=network.target
Wants=network.target

[Service]
Type=notify
NotifyAccess=main
ExecStart=/usr/sbin/mosquitto -c /etc/mosquitto/mosquitto.conf
ExecReload=/bin/kill -HUP $MAINPID
Restart=on-failure
ExecStartPre=/bin/mkdir -m 740 -p /var/log/mosquitto
ExecStartPre=/bin/chown mosquitto: /var/log/mosquitto
ExecStartPre=/bin/mkdir -m 740 -p /var/run/mosquitto
ExecStartPre=/bin/chown mosquitto: /var/run/mosquitto

[Install]
WantedBy=multi-user.target

The mosquitto.conf file is configured as:

# Place your local configuration in /etc/mosquitto/conf.d/
#
# A full description of the configuration file is at
# /usr/share/doc/mosquitto/examples/mosquitto.conf.example

pid_file /var/run/mosquitto/mosquitto.pid

persistence true
persistence_location /var/lib/mosquitto/

log_dest file /var/log/mosquitto/mosquitto.log

include_dir /etc/mosquitto/conf.d

listener 1883

log_type error
log_type notice
log_type information
log_type debug
log_type all
log_dest topic 
log_type warning

allow_anonymous false
connection_messages true
max_keepalive 10
log_timestamp true
log_timestamp_format %Y-%m-%d|%H:%M:%S

password_file /etc/mosquitto/pwfile

####################################################
# MOSQUITTO LISTENER WITH SLL
####################################################

listener 8883
protocol mqtt
allow_anonymous false

#PARA BROKER EN PC
cafile /etc/mosquitto/certs/ca.crt
keyfile /etc/mosquitto/certs/server.key
certfile /etc/mosquitto/certs/server.crt

#PARA BROKER EN RASPBERRY PI 3
#cafile /etc/mosquitto/certs/ca_pi.crt
#keyfile /etc/mosquitto/certs/server_pi.key
#certfile /etc/mosquitto/certs/server_pi.crt

tls_version tlsv1.2

When I ran systemctl status mosquitto from the terminal, it showed me the following message...

● mosquitto.service - Mosquitto MQTT Broker
   Loaded: loaded (/etc/systemd/system/mosquitto.service; enabled; vendor preset: enabled)
   Active: activating (auto-restart) (Result: exit-code) since mar 2020-12-22 13:06:13 -04; 5s ago
     Docs: man:mosquitto(8)
           man:mosquitto.conf(5)
  Process: 22889 ExecStart=/usr/sbin/mosquitto -c /etc/mosquitto/mosquitto.conf (code=exited, status=1/FAILURE)
 Main PID: 22889 (code=exited, status=1/FAILURE)

dic 22 13:06:13 carmenmoncada systemd[1]: 

I don't know what is happening, could anybody help me with this? Thanks in advance Regards.