Fatal Error: composer.lock was created for PHP version 7.4 or higher but the current PHP version is 7.3.11

Question

I want to create a Symfony CRUD application. These are the steps I did:

• Downloaded and installed XAMPP from here with PHP 7.3.11 https://www.apachefriends.org/

Answer 1

I had this problem in the Azure WebApp I solved by setting the CGI to the correct version

   <handlers>
        <remove name="PHP74_via_FastCGI"/>
        <add name="PHP74_via_FastCGI" path="*.php" verb="GET, PUT, POST, DELETE, HEAD, OPTIONS" modules="FastCgiModule"
             scriptProcessor="D:\Program Files\PHP\v7.4\php-cgi.exe" resourceType="Either" requireAccess="Script"/>
    </handlers>

Answer 2

My problem was updating php version with sudo update-alternatives --config php didn't update php-cgi.

Symfony CLI was still using the old version of php-cgi:

symfony local:php:list
┌─────────┬───────────┬────────────┬─────────┬────────────────┬─────────┬─────────┐
│ Version │ Directory │  PHP CLI   │ PHP FPM │    PHP CGI     │ Server  │ System? │
├─────────┼───────────┼────────────┼─────────┼────────────────┼─────────┼─────────┤
│ 7.2.34  │ /usr      │ bin/php7.2 │         │                │ PHP CLI │         │
│ 7.3.23  │ /usr      │ bin/php7.3 │         │ bin/php-cgi7.3 │ PHP CGI │         │
│ 7.4.11  │ /usr      │ bin/php7.4 │         │ bin/php-cgi7.3 │ PHP CGI │ *       │
└─────────┴───────────┴────────────┴─────────┴────────────────┴─────────┴─────────┘

I solved it by updating php-cgi:

sudo apt-get install -y php-cgi