Last modified: 2014-06-27 20:46:26 UTC
The MediaWiki software shouldn't accept uploaded files if:
1-The uploader entered a blank summary.
2-The uploader didn't choose a license from the drop-down menu (which contains licenses listed at MediaWiki:Licenses).
If the above conditions are satisfied then an error message should appear to the user saying that he should select a license.
This will decrease the enormous number of uploaded files with missing licenses.
Licence information is optional. There has been some discussion of an improved upload wizard which steps through the licence checking process, among other things.
On all Wikimedia projects I know, license info is absolutely mandatory. However:
* The appropriate license may not be a standard choice - in that case it has to be entered manually into the description, and the license selector should be left at "none".
* Same goes for uploading new versions of an existing image (selecting a license has no effect in that case anyway)
* And also: if the software would deny upload if no license (or a "bad" license) was selected, people would simply pick *some* license, so the upload goes through. Uploaded images with missing or bad license are easy to find and to handle. Mistagged images are much harder to identify and to deal with.
So, while it seems silly at the first glance to explicitly offer "bad" options, it's the right thing in practice, IMHO. Wizard-based uploads would be cool, at least as an option (and perhaps mandatory for new users, i.e. users without "autoconfirmed").
If you really need to do so, use JS for checking of the upload form.
Related: https://gerrit.wikimedia.org/r/#/c/134509/2 (I465daaff4aed4b484a1f4707fe57d45c0e9ce6cd)