I'm writing this here as a reference for others who run into this issue, because it took me a while before I figured it out. Lib mpdecimal has been removed from the Ubuntu 24.04 package repository: https://tracker.debian.org/pkg/mpdecimal So you need to install it from source in Ubuntu 24.04. Here are the required steps: - Download mpdecimal here: https://www.bytereef.org/mpdecimal/download.html - Unpack and cd into the folder with the sources - run `./configure --prefix=/usr/local` - run `make` - run `sudo make install` Now you can execute `pecl install decimal` again.