English translation of the article in my last post:
( https://www.innosons.nl/bestandsrechten-prestashop-file-permissions/ )
File rights for prestashop
Setting the correct file permissions on your Prestashop server is important for trouble-free and safe operation of your web store. The rights of your files (file rights in English) determine who can read, write and execute files and folders on your server. This is not only important to ensure the safety of your Prestashop store, but essential to keep the frontend and backend from Prestashop to the requirement.
Common problems are modules that do not work and problems with uploading images and other files such as themes and modules. You can set your public file or folder via your FTP program or only give the owner access to certain read, write and export rights to files and folders. For Prestashop we set the file permission for the directories below to 644 for files and 755 for folders. 644 ensures that the server owner can both write and read the files, but the files can only be read publicly. 755 ensures that the directories alone cannot be described by public rights.
Quote
Set (up to and including Prestashop 1.6) the relevant folders and underlying folders to 755, and only the underlying files in these folders to 644:
config / cache / log / img / mails / modules / themes / your_theme / long / themes / your_theme / pdf / lang / themes / your_theme / cache / translations / upload/ Download/
Quote
Set (from Prestashop 1.7) the underlying folders and underlying folders to 755, and only the underlying files in these folders to 644:
config / cache / log / img / mails / modules / themes / your_theme / long / themes / your_theme / cache / translations / upload/
Now the file rights of file rights would no longer be the cause of issues with your Prestashop webshop. If you still have problems, you can always contact us to see if we can help you further with your web store.
Last but not least: Switch off debug mode in Advanced Parameters > Performance
Hope this helps guys!