安装laravel依赖的时候composer报错问题

composer 配置如下：

执行 composer update的时候报错：
Content-Length mismatch, received 15988 bytes out of the expected 435637
https://packagist.phpcomposer.com could not be fully loaded, package information was loaded from the local cache and may be out of date

网上搜索答案全都是说的是镜像源的错误，换成国内的镜像报错：
"https://repo.packagist.org/p/illuminate/support.json" does not contain valid JSON
Parse error on line 1:

^
Expected one of: 'STRING', 'NUMBER', 'NULL', 'TRUE', 'FALSE', '{', '['
https://packagist.phpcomposer.com could not be fully loaded, package information was loaded from the local cache and may be out of date

求教下，应该怎么解决

手工下载 "https://repo.packagist.org/p/illuminate/support.json"
看看这个文件正确么