I've got a problem with a website that i have inherited from another developer, it's Magento 2.3.2 with quite a few extensions installed... The majority of the extensions are installed at /app/code - so manually installed via FTP but 1 extension is installed at /vendor - so installed via composer and the server doesn't have composer installed?
I am guessing the previous dev started work on the site on a server with composer and then moved it to a server without composer... anyway the 1 extension in the /vendor folder (a Sagepay payment processing extension) is causing problems and needs updating or removing and the new version installing via FTP - but how??