I had the site not working (19/7/2020) because of the Crayon syntax highlighter plugin for wordpress that has not been updated since the last 3 years. You can find a new version working (not official) here: new Crayon plugin.
Be careful, I tried first to follow the instruction to modify the existing files of the plugin changing just the lines of code in this example here. Until the last part (with const values) the plugin worked again, but with the last part (that was not necessary I think, I messed up something, probably declaring 2 times a variable, and the site was not showing again and I could not even go into the wp-admin. Fortunately I had filezilla with the site credential memorized, so that I deleted the folder with crayon and the site worked again (phew). Crayon was not working of course, so I tried to install the plugin from the link above and it worked, the site is working, the wp-admin is accessible and the crayon pluugin still does his job. So, before you do anything, I suggest you to download filezilla and in the file / site management put the credential for the site, so that, if something goes wrong, you go back and delete the folder with Crayon into the plugin folder and then you reinstall it from wordpress like I did.
