Unable to install php7.4-dev on Ubuntu 18.04

Question

Trying to install the php7.4-dev extension, but getting the following error:

E: Unable to locate package php7.4-dev
E: Unable to find any packages via glob 'php7.4-dev'
E: Unable to find any package via regex 'php7.4-dev'

When I run apt show php, the following is displayed:

Package: php
Version: 1:7.2 60ubuntu1
Priority: optional
Category: php
Source: php-defaults (60ubuntu1)
Source: Ubuntu
Maintained by: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
Original maintainer: Debian PHP Maintainers <pkg-php-maint@lists.alioth.debian.org>
Bug: https://bugs.launchpad.net/ubuntu/ filebug
Installed size: 12.3 kB
Dependencies: php7.2
Support: 5 years
Download size: 3,084 B
APT source: http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages
Description: Server-side, HTML-embedded scripting language (default)
 PHP (recursive abbreviation for PHP: Hypertext Preprocessor) is a widely used open source general-purpose scripting language, especially suitable for web development and can be embedded in HTML.
 .
 This package is a dependency package and depends on Ubuntu's default PHP version (currently 7.2). 

I updated the software source using the following command:

sudo add-apt-repository ppa:ondrej/php
sudo apt update

After running apt show php again, I received the same message as before, the version still hadn't changed and it still showed PHP 7.2.

However, I get the same result every time, and unfortunately, I cannot install php7.4-dev.

sudo add-apt-repository ppa:ondrej/php sudo apt update apt display php

Answer 1

I ran into the same problem to some extent and for some reason ppa:ondrej/php didn't work on Ubuntu 18.04. As mentioned in this article, after adding the following repository, I successfully installed php7.4

sudo add-apt-repository ppa:sergey-dryabzhinsky/php74
sudo add-apt-repository ppa:sergey-dryabzhinsky/php7-modules
sudo add-apt-repository ppa:sergey-dryabzhinsky/backports
sudo add-apt-repository ppa:sergey-dryabzhinsky/packages