php8.1-mbstring causes startup warning on Ubuntu 18.04

[spideyfusion]

Frequently asked questions

• I have read Frequently Asked Questions

Describe the bug

After adding the php8.1-mbstring to an existing PHP installation, the following warning can be seen when running PHP from CLI:

user@ubuntu:~$ php -m
PHP Warning:  PHP Startup: ^(text/|application/xhtml\+xml) (offset=0): unrecognised compile-time option bit(s) in Unknown on line 0

The extension loads fine though because I can utilize the mb_ functions as expected.

Expected behavior

The warning above is not present on PHP startup.

Distribution (please complete the following information):

• OS: Ubuntu 18.04
• Architecture: amd64
• Repository: Ubuntu PPA

Package(s) (please complete the following information):

php8.1-mbstring:
  Installed: 8.1.0~rc5-1+ubuntu18.04.1+deb.sury.org+2
  Candidate: 8.1.0~rc5-1+ubuntu18.04.1+deb.sury.org+2
  Version table:
 *** 8.1.0~rc5-1+ubuntu18.04.1+deb.sury.org+2 500
        500 http://ppa.launchpad.net/ondrej/php/ubuntu bionic/main amd64 Packages
        100 /var/lib/dpkg/status

Additional context

I can't reproduce this on Ubuntu 21.10.

[oerdnj]

That is not a packaging issue and needs to be reported directly to PHP. Feel free to add the link to the PHP bug here afterwards.

[spideyfusion]

Just an update that the issue occurred due to outdated pcre2 libraries on the system. Once I installed the latest available versions, the problem disappeared:

sudo apt-get install --only-upgrade libpcre2-16-0 libpcre2-32-0 libpcre2-8-0 libpcre2-dev libpcre2-posix2