Your requirements could not be resolved to an installable set of packages.
Problem 1
- Installation request for laravel/horizon v1.4.3 -> satisfiable by laravel/horizon[v1.4.3].
- laravel/horizon v1.4.3 requires ext-pcntl * -> the requested PHP extension pcntl is missing from your system.
To enable extensions, verify that they are enabled in your .ini files:
- E:\laragon\bin\php\php-7.2.11-Win32-VC15-x64\php.ini
You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.
解决： composer install --ignore-platform-reqs
原文：https://www.cnblogs.com/greycdoer0/p/10506731.html