Package php7.2-mbstring unmet dependencies in Ubuntu 18.04

Question

Try to install php-mbstring for mediawiki setup.

already added after first attempt universe repository: Package php7.2-mbstring missing in Ubuntu 18.04

But gives me hard time Here details:

usertilo@myserver4:~$ sudo apt-get install php-mbstring
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 php-mbstring : Depends: php7.2-mbstring but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

usertilo@myserver4:~$ sudo apt-get install php7.2-mbstring
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 php7.2-mbstring : Depends: php7.2-common (= 7.2.3-1ubuntu1) but 7.2.7-0ubuntu0.18.04.2 is to be installed
E: Unable to correct problems, you have held broken packages.

usertilo@myserver4:~$ uname -a
Linux myserver4 4.15.0-29-generic #31-Ubuntu SMP Tue Jul 17 15:39:52 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

usertilo@myserver4:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.1 LTS
Release:        18.04
Codename:       bionic

usertilo@myserver4:~$ sudo apt-get install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

usertilo@server4:~$ sudo apt-get install php7.2-common
Reading package lists... Done
Building dependency tree
Reading state information... Done
php7.2-common is already the newest version (7.2.7-0ubuntu0.18.04.2).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

• update add info requested from comments

usertilo@myserver4:~$ sudo apt-cache policy php7.2-common php7.2-mbstring
php7.2-common:
  Installed: 7.2.7-0ubuntu0.18.04.2
  Candidate: 7.2.7-0ubuntu0.18.04.2
  Version table:
 *** 7.2.7-0ubuntu0.18.04.2 500
        500 http://archive.ubuntu.com/ubuntu bionic-security/main amd64 Packages
        500 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     7.2.3-1ubuntu1 500
        500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages
php7.2-mbstring:
  Installed: (none)
  Candidate: 7.2.3-1ubuntu1
  Version table:
     7.2.3-1ubuntu1 500
        500 http://archive.ubuntu.com/ubuntu bionic/universe amd64 Packages

usertilo@myserver4:~$ cat /etc/apt/sources.list
deb http://archive.ubuntu.com/ubuntu bionic main universe
deb http://archive.ubuntu.com/ubuntu bionic-security main
# deb-src http://archive.ubuntu.com/ubuntu bionic universe
deb http://archive.ubuntu.com/ubuntu bionic-updates main

usertilo@myserver4:~$ cat /etc/apt/sources.list.d/*
cat: '/etc/apt/sources.list.d/*': No such file or directory

Solution

You are missing some necessary channels from sources.list. Do sudo gedit /etc/apt/sources.list and make it look like this:

deb http://archive.ubuntu.com/ubuntu bionic main multiverse restricted universe
deb http://archive.ubuntu.com/ubuntu bionic-security main multiverse restricted universe
deb http://archive.ubuntu.com/ubuntu bionic-updates main multiverse restricted universe

Save and exit. Then update your repository:

sudo apt update

Then install php-mbstring:

sudo apt install php7.2-mbstring

Comments

[Thomas Ward]

Show us the output of the following, please, I'd like to see whether having different repositories enabled or disabled may be the cause of your problems, and this will help shed some light: apt-cache policy php7.2-common php7.2-mbstring (Also, FYI, Universe is enabled by default on Ubuntu 18.04)

[Socrates]

@TiloBunt What sources do you have in /etc/apt/sources.list? And same question for the sources in /etc/apt/sources.list.d/*. Those are the sources you get all your packages from. So make sure, that all looks alright. Get the repository of the package you want to install and check whether you have its source within the mentioned lists.

[TiloBunt]

@ThomasWard and Socrates, added info to my question. let me know if I should check anything else. It's a brand new install

[TiloBunt]

tried this but same result.

[Thomas Ward]

Sounds like your system is not configured properly then. Show us the apt-cache policy output from the same command I asked about in comments as an edit to your question again, because it looks like your repos are not getting updated

[TiloBunt]

appreciate your help. The adding of the restricted fixed it for now and I'm good. The system was a new install on VM so not sure how I can mess up the configuration that quick but might have been. Cheers

[Redbob]

These commands doesn't worked for me. The error is the same. I had to download http://security.ubuntu.com/ubuntu/pool/universe/p/php7.2/php‌​7.2-mbstring_7.2.15-‌​0ubuntu0.18.04.1_amd‌​64.deb and install it by dpkg -i command

[Jeff Lange]

Thank you for this fix, it only took me a few hours to figure out this was the solution.