Laravel 无法声明类 Symfony\Component\HttpFoundation\AcceptHeader，因为该名称已在使用中

Question

我刚刚接手了几个月前用 Laravel 制作的一个项目。该项目还使用了 Laravel Voyager - 管理面板包。

浏览到http://example.com/admin 后，我遇到了一个莫名其妙的奇怪错误，我也不确定如何调试它。它看起来像这样：

Fatal error: Cannot declare class Symfony\Component\HttpFoundation\AcceptHeader, because the name is already in use in /c/Users/User/Code/example-website/vendor/symfony/http-foundation/AcceptHeader.php on line 22

Fatal error: Uncaught Error: Class 'Symfony\Component\HttpFoundation\AcceptHeaderItem' not found in /c/Users/User/Code/example-website/vendor/symfony/http-foundation/AcceptHeader.php:61 Stack trace: #0 [internal function]: Symfony\Component\HttpFoundation\AcceptHeader::Symfony\Component\HttpFoundation\{closure}(Array) #1 /c/Users/User/Code/example-website/vendor/symfony/http-foundation/AcceptHeader.php(57): array_map(Object(Closure), Array) #2 /c/Users/User/Code/example-website/vendor/symfony/http-foundation/Request.php(1664): Symfony\Component\HttpFoundation\AcceptHeader::fromString('text/html,appli...') #3 /c/Users/User/Code/example-website/vendor/laravel/framework/src/Illuminate/Http/Concerns/InteractsWithContentTypes.php(54): Symfony\Component\HttpFoundation\Request->getAcceptableContentTypes() #4 /c/Users/User/Code/example-website/vendor/laravel/framework/src/Illuminate/Http/Concerns/InteractsWithContentTypes.php(44): Illuminate\Http\Request->wantsJson() #5 /c/Users/User/Code/example-website/vendor/laravel/framework/src/Illumina in /c/Users/User/Code/example-website/vendor/symfony/http-foundation/AcceptHeader.php on line 61

这个错误是意料之中的，我以前在我的项目中（或其他任何地方）从未见过它。

如何调试这个问题？

Answer 1

作为健全性检查，删除vendor 目录，然后运行composer install 以重新获取依赖项并查看错误是否已解决。如果没有，请尝试 composer update 获取可能已解决此问题的最新版本的依赖项。