How to remove the error Calling undefined function curl_init ()?

Solution:This error occurs when the cURL library is not installed on your system or not included in your PHP installation. 
Install the cURL library to resolve this error.
  • For Linux - Terminal command:
    sudo apt-get install php-curl 
  • For Windows:
    Download cURL library from official site
    Go to php.ini file and delete; mark the beginning of the next line:
    ; extension = php_curl.dll 
  • Link:http://php.net/manual/en/ curl.installation.php
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