Links to other threads not working when originally they did?

[MNettersForNoahAndFiona]

I've just noticed that some links posted on threads are no longer working and a 'Error 404 oops sorry about this but we seem to have lost this page' notice appears. They certainly did work when originally posted because I always check via preview before posting. They are links posted on threads to link to other Mumsnet threads. Is this another problem with the Mumsnet 'upgrade'?

For example, this has appeared in place of a link which originally worked

class="underline">ibeing_unreasonable/4537366-aibu-to-want-to-know-the-truth-about-this

There are numerous examples.

It's rather strange that every or almost every link to that thread about Noah Donohoe has changed and stopped working. Anyone would think MI5 are on Mumsnet joking, not joking

I reported it to MNHQ and even they are having trouble making the newly-broken links to the thread about Noah work again! They've flagged it to their Tech team.

Thread about Noah, link hopefully working now:
www.mumsnet.com/talk/am_i_being_unreasonable/4537366-aibu-to-want-to-know-the-truth-about-this

Hi @MNettersForNoahAndFiona is this all sorted now?

Mostly, thank you, @YetAnotherBeckyMumsnet - I think just one still needs tinkering with, so I'll report that post with the relevant information.

What caused the problem?