Assuming that this is about https://meta.wikimedia.org/wiki/Event:Wiki_Loves_Public_Domain, the actual history tells a different story: the page was created, in the mainspace, by User:MichellevL (WMNL). So, the problem is not that the page was moved, but that it was created by someone other than the person who then tried to enable registration. You'd see the same thing for a newly created page (and no page moves). So, unless I'm missing something, this is all working as intended.

With that being said, I think it wouldn't be unreasonable to look into ways to, under specific circumstances, let other people enable registration. For example, we could let admins do this regardless of whether they created the page. I think this was maybe mentioned once or twice in team conversations in the past, but I can't find any task about it.

(Also, the error message should probably explicitly say that the user can't enable registration because they did not create the page)

I believe if somebody with Event organizer role would use the link Special:EnableEventRegistration, the application should grant the tole of the "enabler of the event" instead of the refusing the page creator, not having the organiser role.

To solve the problem for now, I have renamed the original page to a subpage, and replaced the redirect by the original text. I was subsequently able to enable the event registration button. I have attributed the original authors in the talk page of the event.

Strange: The creator of the original page, User:MichellevL (WMNL), did have the Event organizers right, but still the event registration could not be enabled, by somebody else, also having the Event organizers role.

In T396931#10933997, @Geertivp wrote:

I believe if somebody with Event organizer role would use the link Special:EnableEventRegistration, the application should grant the tole of the "enabler of the event" instead of the refusing the page creator, not having the organiser role.

Letting anyone with the event-organizer rights enable registration on any page is a significant change to the trust model, and not something I would do lightly. From a purely technical point of view, there's no way to tell between an event page that a friend/collaborator of yours created, and any other page in the Wikipedia namespace for example.

I think the immediate technical action items would be to:

• Update the error text so that it clarifies what's going on (not entirely trivial because there are a few more things going on, but doable)
• Consider creating a separate user right, assigned to administrators by default, that would let them enable registration on any valid page, regardless of the creator