Hey Everyone, I did an upgrade today on our server. We were running version 19.05 on stretch, and we needed to upgrade to buster and I decided to get up to the latest stable Koha release at the same time. The upgrade seemed to go OK but now when I go to our OPAC and do a search I get no results, and if I click on a link for recently added items I get an internal server error. There are some Perl Modules showing as not installed - Locale::XGettext::TT2 , Text::CSV::Unicode , Selenium::Remote::Driver , Test::DBIx::Class, HTTPD::Bench::ApacheBench . There was a warning on the System Information tab about the <lockdir> not being defined in koha-conf.xml so I added that to the config section in there and that warning is now gone. I thought this might be related to plack. If I enter koha-plack -stop <instance> it returns Stopping Plack daemon for <instance> When I enter koha-plack -disable <instance> it returns Plack not disabled for <instance> OPAC Plack not disabled for <instance> Intranet With Plack stopped the error changes to Service Unavailable I tried commenting out the Include /etc/koha/apache-shared-opac-plack.conf line from the apache config and restarting apache, but still got Service Unavailable . /var/log/koha/<instance>/opac-error.log shows this repeatedly [Wed Feb 17 17:03:58.912977 2021] [proxy_http:error] [pid 4810] [client 185.191.171.3:37140] AH01114: HTTP: failed to make connection to backend: httpd-UDS I'm not really sure what logs I should be looking at to troubleshoot this. Thanks, Doug Dearden Director / Information Technology School for Advanced Research (SAR) PO Box 2188 / Santa Fe / NM / 87504-2188 505-954-7220 (work) / 505-690-1535 (cell) www.sarweb.org<http://www.sarweb.org/> EXPLORING HUMANITY. UNDERSTANDING OUR WORLD. Receive the SAR monthly E-News: SIGN UP HERE <https://sarweb.org/about/e-news-signup/>