Error starting apache2 service after installing mod-qos.
There was installed apache2 and after installed libapache2-mod-qos. Saw the
following error in output:

apache2_invoke: Enable module qos
apache2_reload: Your configuration is broken. Not restarting Apache 2
apache2_reload: apache2: Syntax error on line 146 of
/etc/apache2/apache2.conf: Syntax error on line 1 of
/etc/apache2/mods-enabled/qos.load: Cannot load
/usr/lib/apache2/modules/mod_qos.so into server:
/usr/lib/apache2/modules/mod_qos.so: undefined symbol: pcre_free

Full output:
root@4cc791a5ed7d:/# apt-get install libapache2-mod-qos
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
  libpcre3 libpng16-16
The following NEW packages will be installed:
  libapache2-mod-qos libpcre3 libpng16-16
0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 849 kB of archives.
After this operation, 1970 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://deb.debian.org/debian bookworm/main amd64 libpcre3 amd64
2:8.39-15 [341 kB]
Get:2 http://deb.debian.org/debian bookworm/main amd64 libpng16-16 amd64
1.6.39-2 [276 kB]
Get:3 http://deb.debian.org/debian bookworm/main amd64 libapache2-mod-qos
amd64 11.63-1+b2 [233 kB]
Fetched 849 kB in 0s (39.8 MB/s)
debconf: delaying package configuration, since apt-utils is not installed
Selecting previously unselected package libpcre3:amd64.
(Reading database ... 9844 files and directories currently installed.)
Preparing to unpack .../libpcre3_2%3a8.39-15_amd64.deb ...
Unpacking libpcre3:amd64 (2:8.39-15) ...
Selecting previously unselected package libpng16-16:amd64.
Preparing to unpack .../libpng16-16_1.6.39-2_amd64.deb ...
Unpacking libpng16-16:amd64 (1.6.39-2) ...
Selecting previously unselected package libapache2-mod-qos.
Preparing to unpack .../libapache2-mod-qos_11.63-1+b2_amd64.deb ...
Unpacking libapache2-mod-qos (11.63-1+b2) ...
Setting up libpcre3:amd64 (2:8.39-15) ...
Setting up libpng16-16:amd64 (1.6.39-2) ...
Setting up libapache2-mod-qos (11.63-1+b2) ...
apache2_invoke: Enable module qos
apache2_reload: Your configuration is broken. Not restarting Apache 2
apache2_reload: apache2: Syntax error on line 146 of
/etc/apache2/apache2.conf: Syntax error on line 1 of
/etc/apache2/mods-enabled/qos.load: Cannot load
/usr/lib/apache2/modules/mod_qos.so into server:
/usr/lib/apache2/modules/mod_qos.so: undefined symbol: pcre_free
Processing triggers for libc-bin (2.36-9) ...

I read from
https://unix.stackexchange.com/questions/65492/debian-installing-mod-qos-on-apache-results-in-error-on-start

There  Jenny D suggests mod_qos depends on mod_ssl to be loaded before.
I've tried this with NO success:
a2enmod ssl
cd /etc/apache2/mods-enabled/
mv ssl.load 00_ssl.load
systemctl stop apache2
systemctl start apache2

Workaround that worked for me as of Debian 12.1 has been:
a2dismod qos

severity 1039898 critical
thanks

This makes the package unusable in Debian 12, apparently

People noticed in https://forums.debian.net/viewtopic.php?t=155302

tags 1039898 - sid trixie
thanks

Hi,

The package is only unusable in stable (bookworm).

But, you can use bookworm-backports [0] to install the same
testing/unstable version.

It was fixed in testing/unstable by #1000072 [1].

So, I'm removing sid and trixie tags from this bug report.

Cheers,


[0] https://tracker.debian.org/news/1530133/accepted-libapache2-mod-qos-1174-1bpo121-source-amd64-into-stable-backports/
[1] https://bugs.debian.org/1000072