Please describe what "doesn't work" exactly means.
For general information, see https://www.mediawiki.org/wiki/How_to_report_a_bug

Is shown a blank page instead of the regular registration one (try to follow the links above)

I've just noticed that the above problem occurs on Chrome and Safari but on FF and IE8 works correctly.

@Andyrom75 wrote:

Is shown a blank page instead of the regular registration one
I've just noticed that the above problem occurs on Chrome and Safari but on FF and IE8 works correctly.

I cannot reproduce. I tried on my desktop computer on Linux with Firefox 38 and Google Chrome 43, and both logged out and logged in).

Which operating system? Which device(s)? Are other users affected? Any links to such reports by other users?

(try to follow the links above)

I did that and I did not see anything surprising, hence I asked.
People cannot always reproduce bugs, hence bug reports need to describe what the actual and expected outcome is. :)

I've tried with Chrome 43 on a laptop with Windows 7 and with Safari on an iPad.

Now I think I've got it. The problem occurs when logged in.
I've just tried with FF unlogged and the page is regularly shown, but after the login the page turn blank.

completely blank page and yet I see nothing coming up at fluorine:/a/mw-log/exception.log (or hhvm.log) when it happens

Occurs on other wikis such as enwiki too: https://en.m.wikipedia.org/wiki/Special:UserLogin/signup

When I try this locally I get:

Fatal error: Call to undefined method UserAccountCreateMobileTemplate::addInputItem() in /home/alex/Development/MediaWiki/extensions/AntiSpoof/AntiSpoofHooks.php on line 79

Looks like an incompatibility between MW core's UsercreateTemplate (which AntiSpoof expects to get through the UserCreateFormHook hook) and MobileFrontend's equivalent (UserAccountCreateMobileTemplate or UserLoginAndCreateTemplate)

Hmm, i don't see an empty page :/

I'm currently not seeing blank pages for any of the URLs mentioned in the comments both logged in and logged out.

Change 218948 had a related patch set uploaded (by Florianschmidtwelzow):
Inherit UsercreateTemplate for User{login|create} templates to fix T102775

https://gerrit.wikimedia.org/r/218948

But it appears that @Florian is!

@phuedx I only see it locally with AntiSpoof (no configuration, so anything default), but it makes sense and we should do the above change anyhow :)

Change 218948 merged by jenkins-bot:
Inherit UsercreateTemplate for User{login|create} templates to fix T102775

https://gerrit.wikimedia.org/r/218948

• https://gerrit.wikimedia.org/r/218948 (branch master): WMF-deploy-2015-06-16_(1.26wmf10)