Laravel 5.5 application not booting anymore with “A facade root has not been set.”

问题

For some reason one of our applications isn't booting anymore. The stack trace looks like this:

PHP Fatal error:  Uncaught RuntimeException: A facade root has not been set. in /app/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php:218
Stack trace:
#0 /app/app/Exceptions/Handler.php(43): Illuminate\Support\Facades\Facade::__callStatic('get', Array)
#1 /app/vendor/laravel/framework/src/Illuminate/Foundation/Console/Kernel.php(352): App\Exceptions\Handler->report(Object(Dotenv\Exception\InvalidFileException))
#2 /app/vendor/laravel/framework/src/Illuminate/Foundation/Console/Kernel.php(123): Illuminate\Foundation\Console\Kernel->reportException(Object(Dotenv\Exception\InvalidFileException))
#3 /app/artisan(37): Illuminate\Foundation\Console\Kernel->handle(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#4 {main}
  thrown in /app/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php on line 218

I'm sure there's something that changed and stopped the application from booting. But I have no clue what exactly happened. Any help is greatly appreciated.

回答1:

The solution was quiet simple but difficult to find.

.env variables should not be assigned as KEY="VALUE" and also too many spaces can crash the initialisation of the .env

i.e: DB_HOST= mysql

Just correct the .env and it should work like a charme

回答2:

As a sanity check, completely delete your vendor directory and then re-install (or update) your dependencies. It is possible a file in there was mistakenly changed and is now causing problems.

rm -rf vendor
composer update

来源：https://stackoverflow.com/questions/54659453/laravel-5-5-application-not-booting-anymore-with-a-facade-root-has-not-been-set