PHP 反复重装都没有mbstring扩展

Gerardo

Starting php-fpm [28-Jun-2023 19:25:12] NOTICE: PHP message: PHP Warning:  PHP Startup: Unable to load dynamic library 'mbstring' (tried: /usr/local/php/lib/php/extensions/no-debug-non-zts-20200930/mbstring (/usr/local/php/lib/php/extensions/no-debug-non-zts-20200930/mbstring: cannot open shared object file: No such file or directory), /usr/local/php/lib/php/extensions/no-debug-non-zts-20200930/mbstring.so (/usr/local/php/lib/php/extensions/no-debug-non-zts-20200930/mbstring.so: cannot open shared object file: No such file or directory)) in Unknown on line 0
done


扩展目录下没有so文件。

lnmp 1.9版。 PHP选的是8.0版。
UBUNTU 20