Solved – docker configuration error on mbstring for php:7.4 fpm

Error Description

checking for oniguruma... no
configure: error: Package requirements (oniguruma) were not met:

No package 'oniguruma' found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

Alternatively, you may set the environment variables ONIG_CFLAGS
and ONIG_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.
ERROR: Service 'app' failed to build: The command '/bin/sh -c docker-php-ext-install mbstring' returned a non-zero code: 1

Solution:

Remove mbstring from docker-php-ext-install instruction