[php] Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"?

I think it's a version problem, you just have to uninstall the old version of composer, then do a new installation of its new version.

 apt remove composer

and follow the steps:

  1. download the composer from its official release site by making use of the following command.
 wget https://getcomposer.org/download/1.6.3/composer.phar
  1. Before you proceed with the installation, you should rename before you install and make it an executable file.
  mv composer.phar composer
  chmod +x composer
  1. Now install the package by making use the following command.
 ./composer
  1. The composer has been successfully installed now, make it access globally using the following command. for Ubuntu 16
 mv composer /usr/bin/

for Ubuntu 18

 mv composer /usr/local/bin/