Error – custom field filter tutorial

• ohlala

• January 18, 2019 at 8:26 pm

Hi,

I wanted to set up a custom field filter and found this tutorial https://www.advancedcustomfields.com/resources/creating-wp-archive-custom-field-filter/

Unfortunately I get this error.

Fatal error: Uncaught Error: [] operator not supported for strings in /homepages/16/g4345656/htdocs/test/wp-content/themes/blank/functions.php:3

What do you I have to do to get rid of this error and make this code work?