Call to undefined function Illuminate\Queue\pcntl_signal()

This error occurs because the pcntl extension is not installed on your server. You need to install the pcntl extension to use the pcntl_signal() function.

To install the pcntl extension on Linux, you can follow these steps:

1. Open the terminal and run the following command to install the pcntl extension:

sudo apt-get install php-pcntl

1. Restart your web server to apply the changes:

sudo service apache2 restart

1. Verify that the pcntl extension is installed by running the following command:

php -m | grep pcntl

This should output "pcntl" if the extension is installed correctly.

Once the pcntl extension is installed, the error should be resolved and you should be able to run Laravel queue in Linux server via supervisor.