I am able to upload, what error are you getting?
What version of UploadWizard?

Apparently fixed on gerrit change 49690 (according to the commit summary), but unable to assure because of the extremely vague bug description.

Please, refer to http://www.mediawiki.org/wiki/How_to_report_a_bug

Thank you for the link to the gerrit change.
I am not sure what information to put into the description additionally. Please be more specific about what is unclear.

jgerber wrote:

yes https://gerrit.wikimedia.org/r/#/c/49690/ fixes this issue, might be worth to even push this patch out before the next deployment window.

(In reply to comment #3)

Please be more specific about what is unclear.

Good steps to reproduce, an URL to test, browser information, ... :)

(In reply to comment #4)

yes https://gerrit.wikimedia.org/r/#/c/49690/ fixes this issue, might be
worth
to even push this patch out before the next deployment window.

When will the next deploy be?

(In reply to comment #6)

When will the next deploy be?

See https://www.mediawiki.org/wiki/MediaWiki_1.21/Roadmap