Theme Change (Hopefully temporary)

Looks like I will need to change the theme for this site. WordPress tells me I need to update the PHP version but each time I do the site goes to pot and doesn’t even load.

Reverting to default theme and deactivating all plugins worked. Site was up and running just like the other one (which had no problems at all with the PHP version change.)

But as soon as I go back to my Bob Shaw theme. Pfft Kaput.

Default theme until I can create a new one which works.