我的项目是5.4的,使用 composer update 升级到5.5时报如下错误

这是我的composer.json部分 配置
.
.
.
"require": {
"php": ">=5.6.4",
"barryvdh/laravel-debugbar": "~2.4",
"doctrine/dbal": "~2.4",
"laravel/framework": "5.5.*",
"laravel/tinker": "~1.0",
"predis/predis": "^1.1"
},
.
.
.
"scripts": {
"post-root-package-install": [
"php -r \"file_exists('.env') || copy('.env.example', '.env');\""
],
"post-create-project-cmd": [
"php artisan key:generate"
],
"post-install-cmd": [
"Illuminate\\Foundation\\ComposerScripts::postInstall",
"php artisan optimize"
],
"post-update-cmd": [
"Illuminate\\Foundation\\ComposerScripts::postUpdate",
"php artisan optimize"
],
"post-autoload-dump":[
"Illuminate\\Foundation\\ComposerScripts::postAutoloadDump",
"@php artisan package:discover"
]
},
跪求各位帮忙解答一下,谢谢!
bootstrap
目录可写权限不够吧