I am using the standard Filtered HTML text format in a Backdrop site (v 1.26.2, php 8.2x). This is on a development site running on my localhost, although the problem also exists with ckeditor4 on the live version of the same site.
When I click the Configure link in the dropdown next to it, I consistently get an error message:
in_array(): Argument #2 ($haystack) must be of type array, null given
The toolbars are appear and function correctly on the text fields where it is configured, so that is not a problem. I would only like to make some changes to the configuration. It is a multilanguage site using Content Translation, in case that makes any difference.
Any ideas on how to fix it would be welcome.
I would file an issue with this information here:
And then based on the line that is giving the error, I would check that you have at least one translatable text format defined on this page: admin/config/regional/i18n/strings