Will this procedure be notified to all the affected users?

I like @ori's suggestion of "On the next edition of Tech News, include a notice that invites users who were affected by this bug to get in touch if they would like a skin preference to be set globally for their account."

For which he just added the User-notice project.

@Johan: let me know if you want any other information about this/help writing the text.

@Johan: My suggested wording:

Skin Preference incident

• On September 29th there was an accidental removal of users' skin preferences on small and medium sized wikis, defaulting them back to Vector.
• A restoration of the data from a backup was deemed more disruptive than not.
• Effected users who would like their skin preference changed globally can make a request as a comment on Phabricator task T119206 until December 21st, 2015 (4 weeks from the publication of this TechNews).

Sounds good. I'll rephrase it slightly to simplify for non-native speakers ("was deemed more disruptive than not" is pretty difficult to parse if you don't speak English very well, for example), but I don't think there's anything unclear here.

:) thanks

Please change my skin preference to Monobook in all wikis.

Is it possible to change my skin preferences to Monobook only in wikis where I have edits? I changed my preferences (incl. skin) on each wiki when I made my first edit there, and it was very useful for me to be able to distinguish immediately whether my preferences in a given wiki are already configured or not.

In T119206#1838386, @Edgars2007 wrote:

Please change my skin preference to Monobook in all wikis.

Running the script now for all wikis which you have a local account, should be complete in a few minutes.

In T119206#1838714, @NickK wrote:

Is it possible to change my skin preferences to Monobook only in wikis where I have edits?

No that isn't possible I'm afraid. It will only set the preference on wikis in which you have a local account on though, so if you go to a wiki you haven't been to before, you'd get the same effect going forward.

In T119206#1838886, @demon wrote:

Running the script now for all wikis which you have a local account, should be complete in a few minutes.

Thank you

In T119206#1838886, @demon wrote:

No that isn't possible I'm afraid. It will only set the preference on wikis in which you have a local account on though, so if you go to a wiki you haven't been to before, you'd get the same effect going forward.

That's rather annoying. Would it be ok to give a list of wikis where I would like to have monobook back?

In T119206#1870832, @NickK wrote:

In T119206#1838886, @demon wrote:

No that isn't possible I'm afraid. It will only set the preference on wikis in which you have a local account on though, so if you go to a wiki you haven't been to before, you'd get the same effect going forward.

That's rather annoying. Would it be ok to give a list of wikis where I would like to have monobook back?

Sure, that I can do that easily enough!

In T119206#1873407, @demon wrote:

In T119206#1870832, @NickK wrote:

In T119206#1838886, @demon wrote:

No that isn't possible I'm afraid. It will only set the preference on wikis in which you have a local account on though, so if you go to a wiki you haven't been to before, you'd get the same effect going forward.

That's rather annoying. Would it be ok to give a list of wikis where I would like to have monobook back?

Sure, that I can do that easily enough!

Hey @NickK, I was wondering if you still wanted me to take care of this for you. If so just say the word :)

In T119206#1822298, @greg wrote:

• Effected users who would like their skin preference changed globally can make a request as a comment on Phabricator task T119206 until December 21st, 2015 (4 weeks from the publication of this TechNews).

So, it's been 6 weeks actually. I'm closing the task for requests now.

In T119206#1915916, @Nemo_bis wrote:

Was this request page ever announced to people?

Yes, it was at Tech news.

In T119206#1915916, @Nemo_bis wrote:

I still need my preference to be changed back too.

This is the first I see you requesting that even though you've been subscribed to this task from the beginning. We (Chad) can still do it, though.

In T119206#1938966, @Nemo_bis wrote:

I still see interface in Vector on some wiki when I'm logged in.

@Nemo_bis: Which wiki(s) is "some wiki" in order to check?