Cannot read property 'split' of undefined Prestashop 1.7.6.7

[PeterB19]

Hello,

I have a Prestashop 1.7.6.7 installed in production. Lately, the product details page in back office is messed up.

I found this topic wich said to downgrade the php version to PHP 7.2 but it doesn't work in my case and it breaks other components so it's not a valid valid solution for me.

I have exactly the same problem, with dropdowns broken and javascripts errors in console. Especially, the error "Cannot read property 'split' of undefined".

Do you have some solutions to help me please ?

Thank you.