I was following the Laravel 6.x to Laravel 7.x upgrade doc and made the necessary changes. But it is failing and showing the following error. At the time of running composer update there were not 3rd party packages. Then i installed some other packages and after that tried to update again and stuck at this error.
Generating optimized autoload files
> Illuminate\Foundation\ComposerScripts::postAutoloadDump
> @php artisan package:discover --ansi
PHP Fatal error: Uncaught TypeError: Argument 1 passed to Symfony\Component\Process\Process::__construct() must be of the type array, string given, called in phar:///usr/local/bin/composer/src/Composer/Util/ProcessExecutor.php on line 65 and defined in /var/www/html/laravel/laravel-starter/vendor/symfony/process/Process.php:140
Stack trace:
#0 phar:///usr/local/bin/composer/src/Composer/Util/ProcessExecutor.php(65): Symfony\Component\Process\Process->__construct(''/usr/bin/php7....', NULL, NULL, NULL, 300)
#1 phar:///usr/local/bin/composer/src/Composer/EventDispatcher/EventDispatcher.php(245): Composer\Util\ProcessExecutor->execute(''/usr/bin/php7....')
#2 phar:///usr/local/bin/composer/src/Composer/EventDispatcher/EventDispatcher.php(96): Composer\EventDispatcher\EventDispatcher->doDispatch(Object(Composer\Script\Event))
#3 phar:///usr/local/bin/composer/src/Composer/Autoload/AutoloadGenerator.php(312): Composer\EventDispatcher\EventDispatcher->dispatchScript('post-autoload-d...', true, Array, Array)
#4 phar:///usr/local/bin in /var/www/html/laravel/laravel-starter/vendor/symfony/process/Process.php on line 140
Fatal error: Uncaught TypeError: Argument 1 passed to Symfony\Component\Process\Process::__construct() must be of the type array, string given, called in phar:///usr/local/bin/composer/src/Composer/Util/ProcessExecutor.php on line 65 and defined in /var/www/html/laravel/laravel-starter/vendor/symfony/process/Process.php:140
Stack trace:
#0 phar:///usr/local/bin/composer/src/Composer/Util/ProcessExecutor.php(65): Symfony\Component\Process\Process->__construct(''/usr/bin/php7....', NULL, NULL, NULL, 300)
#1 phar:///usr/local/bin/composer/src/Composer/EventDispatcher/EventDispatcher.php(245): Composer\Util\ProcessExecutor->execute(''/usr/bin/php7....')
#2 phar:///usr/local/bin/composer/src/Composer/EventDispatcher/EventDispatcher.php(96): Composer\EventDispatcher\EventDispatcher->doDispatch(Object(Composer\Script\Event))
#3 phar:///usr/local/bin/composer/src/Composer/Autoload/AutoloadGenerator.php(312): Composer\EventDispatcher\EventDispatcher->dispatchScript('post-autoload-d...', true, Array, Array)
#4 phar:///usr/local/bin in /var/www/html/laravel/laravel-starter/vendor/symfony/process/Process.php on line 140
Source of the project is available at: https://github.com/nasirkhan/laravel-starter/tree/v7