我正在尝试安装 Laravel 包名称bitwasp但此包依赖于bcmath. 每当我尝试安装时，它都会给我一个错误。我也尝试使用以下命令安装它：
sudo apt-get install php7.1-bcmath
但每当我这样做时，我的 Ubuntu 也是 17.10 时出现以下错误：
After this operation, 128 kB of additional disk space will be used.
Do you want to continue? [Y/n] Y
Err:1 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-gd amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:2 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-bz2 amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:3 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-opcache amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:4 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-json amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:5 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-mcrypt amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:6 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-zip amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:7 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-curl amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:8 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-xml amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:9 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-mbstring amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:10 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-mysql amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:11 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-readline amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:12 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 libapache2-mod-php7.1 amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:13 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-cli amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:14 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-common amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
Err:15 http://ppa.launchpad.net/ondrej/php/ubuntu artful/main amd64 php7.1-bcmath amd64 7.1.12-2+ubuntu17.10.1+deb.sury.org+2
404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-gd_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-bz2_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-opcache_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-json_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-mcrypt_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-zip_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-curl_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-xml_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-mbstring_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-mysql_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-readline_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/libapache2-mod-php7.1_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-cli_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-common_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php7.1/php7.1-bcmath_7.1.12-2+ubuntu17.10.1+deb.sury.org+2_amd64.deb 404 Not Found
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
已经运行update并且fix-missing没有任何反应，每次我遇到同样的错误。