Comment 9 for bug 1998311

The linked bugzilla issue has 2 files attached with a complete and self-container example of the issue and fix, see

https://bz.apache.org/bugzilla/show_bug.cgi?id=66300#c2
https://bz.apache.org/bugzilla/show_bug.cgi?id=66300#c3
https://bz.apache.org/bugzilla/show_bug.cgi?id=66300#c4

Posting the one showing the issue for posterity:

--- BEGIN DOCKERFILE ---
# syntax=docker/dockerfile:1.3-labs
FROM ubuntu:22.04
RUN apt update && \
    apt install -y make autoconf libtool-bin gcc libaprutil1-dev subversion libpcre3-dev vim patch
RUN svn checkout http://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x httpd-2.4.x && \
    cd httpd-2.4.x/ && \
    svn co http://svn.apache.org/repos/asf/apr/apr/trunk srclib/apr
RUN cd httpd-2.4.x/ && \
    ./buildconf && \
    ./configure --prefix=/opt/httpd-2.4.x && \
    make -j`nproc` && \
    make install
RUN /opt/httpd-2.4.x/bin/apachectl -t
COPY <<EOF /opt/httpd-2.4.x/conf/extra/httpd-hcheck-ajp.conf

LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_ajp_module modules/mod_proxy_ajp.so
LoadModule proxy_hcheck_module modules/mod_proxy_hcheck.so

<VirtualHost *:80>
    ServerAdmin <email address hidden>
    DocumentRoot "/opt/httpd-2.4.x/docs/myapp.example.com"
    ServerName myapp.example.com
    ErrorLog "logs/myapp.example.com-error_log"
    CustomLog "logs/myapp.example.com-access_log" common

    <Proxy balancer://myapp>
        BalancerMember ajp://127.0.0.1:8009/myapp route=app-route timeout=300 ping=3 connectiontimeout=3 hcmethod=CPING
    </Proxy>

    ProxyPass /myapp balancer://myapp stickysession=JSESSIONID

</VirtualHost>
EOF
RUN echo 'Include conf/extra/httpd-hcheck-ajp.conf' >> /opt/httpd-2.4.x/conf/httpd.conf
RUN /opt/httpd-2.4.x/bin/apachectl -t
--- END DOCKERFILE ---

I can post here a modified version using ubuntu's packages instead of compiling apache2 from source if needed.