Matomo 3.12.0 update issue: Undefined index: enable_sites_admin

After updating my Matomo installation using the automatic online process, I first ran into the issue reported in (No entry or class found for 'path.misc.user'), and fixed it by adding line 13 as suggested there. The update proceeded to conclusion. However, now there is an error at the top of my dashboard stating:

“WARNING: /PATHTOINSTALLATION/www/plugins/SitesManager/SitesManager.php(53): Notice - Undefined index: enable_sites_admin - Matomo 3.12.0 - Please report this message in the Matomo forums: https://forum.matomo.org (please do a search first as it might have been reported already) (Module: MultiSites, Action: index, In CLI mode: false)”

where I have replaced the path to my installation with “PATHTOINSTALLATION”. Please help troubleshoot this. If it helps, when the database upgrade prompt came, there was a line on the files having an integrity problem which I missed before I clicked on the continue buttion.

Hi,

Also make sure your global.ini.php contains this line:

Maybe try to replace the whole file with the one from the latest release as it seems like your update got aborted before all files could be replaced.

Thanks Lukas. The problem went away after adding this line.

Unfortunately, my installation stopped working in a few hours, so that fix did not work. I was in a rush, so deleted the entire installation, including all my data, and installed a fresh one.