Warning: Undefined array key "position" in Drupal\facets_summary\Plugin\facets_summary\processor\ResetFacetsProcessor->build() (line 111 of modules/contrib/facets/modules/facets_summary/src/Plugin/facets_summary/processor/ResetFacetsProcessor.php).

As no one has answered this question.
This is due to a change in config.

You probably have this:

processor_configs:
  reset_facets:
    processor_id: reset_facets
    weights:
      build: '30'
    settings:
      link_text: 'Reset all filters'

Somewhere in your config files like facets_summary.facets_summary.[content_type]_facet_summary.yml
It should look like this:

processor_configs:
  reset_facets:
    processor_id: reset_facets
    weights:
      build: '30'
    settings:
      link_text: 'Reset all filters'
      position: null

And the position can be either null/before/after/replace please have a look at the ResetFacetsProcessor for details.
But this should fix your issue.

Kind regards,

Thomas Dik

on my side resaving the facet summary widget helped.

Did you facets_summary_update_8002() run on update ?
Kr

But, answering

Any idea where can i find the settings for $configuration['settings']['position'] ? nothing like that i can find within the facet settings.

should be here:
/admin/config/search/facets/facet-summary/{facets_summary}/edit

i have fixed this issue Warning: Undefined array key "position" in Drupal\facets_summary\Plugin\facets_summary\processor\ResetFacetsProcessor->build() (line 111 of modules/contrib/facets/modules/facets_summary/src/Plugin/facets_summary/processor/ResetFacetsProcessor.php).

Mohd: Thanks for putting together a patch for this. As a reminder, when you upload a patch (or create a merge request) please update the status to "needs review", that will trigger the automated tests and let others know there's a potential fix available.

I'm not sure the patch in #6 covers the scenarios correctly - if the variable exists but is not the values 'before' or 'after' then it won't hit the "else" statement.

How about this?

Can steps to reproduce be added.