Thread:Project:Support desk/Fatal error: Interface 'Psr\Log\LoggerInterface' not found/reply

Hello,

this seems to be NOT 1.23.6, \Psr\Log\LoggerInterface prerequirement was merged yesterday into master branch of MediaWiki core (currently 1.25alpha), so you maybe downloaded MediaWiki from git?

To fix this, you need to install the vendor directory for mediawiki. For this you can just run  if you have shell access and composer installed, or you clone the vendor git repository into your mediawiki root directory:

git clone https://gerrit.wikimedia.org/r/p/mediawiki/vendor.git