samS-20

Problem:
If you're experiencing a fatal error when trying to update/save on an ACF options page, which results in a TypeError because an array is given instead of a string, this might be due to an issue with nested options fields in secondary languages.
Solution:
We recommend trying the workaround provided in the WPML errata. Please ensure to back up your site before making any changes. You can find the detailed steps here: Advanced Custom Fields: Fatal Error when saving nested options fields in secondary languages.

If this solution does not resolve your issue or seems irrelevant due to being outdated or not applicable to your case, please open a new support ticket. We also 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.