Matomo not working after upgrade to 4.8.0

I wonder if anyone can advise, please?

I have just invoked the automatic upgrade option from a link in a verified Matomo advisory email. The basic upgrade worked fine and usually there is a secondary stage where the database needs to be updated too, but not on this occasion.

The result is that the Matamo just times out, with no response at all. Running the upgrade a second time just stated there was a problem but that the latest version was already installed.

Does this need a database update, perhaps?

Any advice will be gratefully received!