As can be seen in this screenshot:
https://commons.wikimedia.org/wiki/File:Screenshot_of_upload_wizard_error.jpeg
the upload wizard is failing for me. It is doing so consistent, and has been for several I amusing Firefox (50.0.1 - the up--to-date version) on a high-spec Windows10 machine, The problem persists, even after I restart my machine. Even if I try to upload more than one image at once, it reports "1 of 1 file uploaded" and does not show the "continue" button.
Reported twice:
* https://commons.wikimedia.org/wiki/Commons:Help_desk#Upload_Wizard_stopped_working
* https://commons.wikimedia.org/wiki/Commons:Village_pump#Upload_wizard_error
Backtrace:
```
NS_ERROR_UNEXPECTED: load.php:47
mw.FirefoggHandler.prototype.start https://commons.wikimedia.org/w/load.php:47:411
mw.UploadWizardUpload.prototype.start https://commons.wikimedia.org/w/load.php:99:396
uw.controller.Upload.prototype.transitionOne https://commons.wikimedia.org/w/load.php:203:409
bound self-hosted
uw.ConcurrentQueue.prototype.executeNext https://commons.wikimedia.org/w/load.php:194:609
uw.ConcurrentQueue.prototype.startExecuting https://commons.wikimedia.org/w/load.php:194:877
uw.controller.Upload.prototype.startQueuedUploads https://commons.wikimedia.org/w/load.php:203:652
uw.controller.Upload.prototype.setUploadFilled https://commons.wikimedia.org/w/load.php:204:991
uw.controller.Upload.prototype.addFile https://commons.wikimedia.org/w/load.php:204:272
uw.controller.Upload.prototype.addFiles/< https://commons.wikimedia.org/w/load.php:204:480
.each https://commons.wikimedia.org/w/load.php:5:226
uw.controller.Upload.prototype.addFiles https://commons.wikimedia.org/w/load.php:204:440
UWControllerUpload/< https://commons.wikimedia.org/w/load.php:201:955
oo.EventEmitter.prototype.emit https://commons.wikimedia.org/w/load.php:588:836
uw.ui.Upload.prototype.setupFileInputCtrl/< https://commons.wikimedia.org/w/load.php:221:214
jQuery.event.dispatch https://commons.wikimedia.org/w/load.php:65:913
jQuery.event.add/elemData.handle https://commons.wikimedia.org/w/load.php:60:459
```