Your requirements could not be resolved to an installable set of packages for laravel

First of all, stop the XAMPP/Wamp and then kindly remove the starting semicolon ( ; ) from your xampp\php\php.ini the following code.

;extension=fileinfo

or in windows with IIS

extension=php_fileinfo.dll

And then restart your XAMPP/Wamp.

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NOTE: For Windows, you can find the file in the C:\xampp\php\php.ini-Folder (Windows) or in the etc-Folder (within the xampp-Folder).

The problem seems to be what the error message says - your system is missing fileinfo PHP extension. Since you're on Windows, open C:\php-7\php.ini file, search for the following line, and remove the beginning ; if exists:

extension=fileinfo

or in windows with IIS

extension=php_fileinfo.dll

Just uncomment extension=fileinfo in php.ini it worked for me even without xampp