Board Thread:Support Requests - Getting Technical/@comment-37915381-20201015185427/@comment-9605025-20201015192550

You can add categories to images (or any file) but going to its file page. You should see the category module at the bottom of the page. You can also add categories by editing the file page's content. This is the content that shows under the about tab on the page. If you are using Special:Upload, there is a summary box which you can use to set the initial page content and thus add categories at the time of upload. However, when doing it this way, you have to use wikitext. For legacy wikis, there is a similar box on Special:MultipleUpload and the description gets applied to all files you are uploading. However, Special:MultipleUpload is not available on UCP.