Cannot create subsite

[JorritK]

Hi Guys,

We have problems to create a sub-site under existing communications sites .

Yes, we have the "create a sub-site" button. But when we fill in the necessary information and click on save, we get errors.

One user gets "We're sorry, an error occured while processing your request", and I get "500 - The request timed out."
We both have sufficient permissions.

But, after the "timed-out error", the site seems to be created. However, it was last modified 120 years ago?

I can't really figure out where to look to resolve this problem

Thanks!

[#2]

There is much we can do here to help you, just open a support ticket with the same info. you have provided here + some screenshots

[#3]

@JorritK Check if this is happening to ALL the Communication Sites? Replicate the same thing in Team sites. You can check the fiddler, but i don't think it will help much, still an initial analysis is required. 

Your only option I would suggest is to raise a MS Ticket with B Severity and provide all the info in ticket itself with screenshots and Fiddler Traces to expedite the resolution.