The Rpi4B has nothing to do with it (ca
n'en a rien à voir - rien du tout !)
Just do the following things:
1. save your old .../skins/Seasons
directory and its content
2. save your old weewx.conf
3. save your old weewx.sdb
e.g. on a USB stick
4. now do a complete new install on the
new RPi (doesn't matter if RPi2, RPi3, RPi4B, just do it !) with
the simulator driver
5. make sure you have a webserver
installed (apache2 or nginx)
6. if you use an extension or special
driver, install that driver/extension
7. once everything works with the
Simulator driver and the Seasons skin,
then
copy the files from your USB stick back
a) .../skins/Seasons and content to
your new ../skins directory either /etc/weewx/skins or
/home/weewx/skins
b) weewx.conf to your new weewx directory (either /etc/weewx or
/home/weewx depending on your installation method
c) weewx.sdb to your new weewx database
directory: either /var/lib/weewx or /home/weewx/archive
start weewx - and it should just run
normally using your old skin definitions, your old weewx.conf and
your old weewx database
then you have upgraded your weewx and
have at the same time kept your configuration and history