Development install errors

Hi,
I have just pulled and upgraded a local and a server install of the Indico development version.
Also a production install.
The production install appears to run fine however the development ones are not.
If I try to edit an existing Conference’s dates or try to create a new one, the input date fields are hidden:

these errors appear in devtools:

Another issue I am getting: when I try to either edit an existing or create a new Contribution, this pops up:

my logs show this:

“POST /api/principals HTTP/1.1” 422 -

any ideas?
Cheers

there is more, creating a Lecture:

and creating a meeting also shows hidden date inputs:

Did you rebuild the client assets?

“POST /api/principals HTTP/1.1” 422 -

In case my comment above does not help: What’s the request payload and response body when this request fails?

no, I didn’t, but now I did and it resolved the issues Thanks!