Ubuntu 20.04 @reboot cronjob doens't run script

I have a vultr server in a ubuntu so 20.04, i'm creating a bash script in the following dir

/startupscripts/apilibro

Inside of the script i need to start my directus server running yarn directus start

!#/bin/bash
cd /var/www/vhosts/librocambio.cl/core.librocambio.cl/apilibro
/usr/bin/yarn directus start

I give chmod 755 to read, write and execute the script, finally i run crontab -e and add the following code to execute when server is restarted

@reboot /startupscripts/apilibro

My problem is that the yarn directus start command doesn't run, when i run locally the command works, but on ubuntu reboot doesn't work, finally i test the bash script adding a line as touch index.js and it works but yarn directus start command doesn't run.

Any idea how to solve this problem?

1st way,

i think you can use the command to check out log of crond

tail -f /var/log/cron.log

the output here might be give you some info.

if there is no cron.log, use this command and restart the rsyslog service

sed -i '/#cron.*/s/^#//g' /etc/rsyslog.d/50-default.conf

systemctl restart rsyslog.service

2nd

perhaps the env of yarn does not match your use who run the crond?

Problem solved, this is what i did to solve my problem.

1. I ran the script manually using bash apilibro, so i notice that yarn wasn't present in my environment variables, i just added as @Artur Medim say.
2. I notice that my nodejs version was 10.x.x by default, when i changed it using nvm it works, but when i rebooted the system or close my ssh terminal, the nodejs version change to the default, so updated correctly my versión to 16.x.x to make sure that this is not happening.

After that i could run the script manually and on cronjob, thank to all for your answers.