V0.40.0 Welcome screen error

First thing I see when logging into v0.40.0, Win10 laptop, FireFox 89.0.2 and on logout a similar screen with "an error occurred" message:

v0.39.4 gives a similar welcome screen:

Hello, I had to user ctrl+F5 to force a reload, it worked afterwards for me.

It looks like a browser cache issue, where certain parts of Metabase is still using an older version, while others are using the latest release.