karenO-2

Problem:
You are trying to add a new custom field using ACF, but encounter an error stating 'Uncaught InvalidArgumentException: item should be a Collection or an array or an object' when attempting to save it. Additionally, an E_ERROR occurs in the WPML plugin.
Solution:
We recommend applying the solution described in the following WPML forum topic: WPML forum topic.
Also, check the errata page for a related issue here: WPML errata page.

If this solution does not resolve your issue or seems outdated, we highly recommend checking related known issues at https://wpml.org/known-issues/, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. If the problem persists, please open a new support ticket at WPML support forum.