Hello Michael,

this is a well known issue, related to the fact that fof is no longer updated and generates deprecations under the latest PHP versions.

There are several ways you can eliminate the warnings:

• change your server PHP.ini settings and set your site error reporting to 'system default' so you can keep getting other warnings and errors,
• change the error reporting setting to 'none' (but is not interesting when in development, as you cannot see if there are actual issues).

The PHP.ini file should have, for the first option,

error_reporting = E_ALL & ~E_DEPRECATED & ~E_STRICT