Facet API pretty paths in combination with solr search form
There are two ways to avoid this issue which depend on module what you use.

1) If Search API module is used. (It was taken from https://www.drupal.org/node/2625298)

function hook_search_api_query_alter(SearchApiQueryInterface $query) {
    $original_keys = $query-&gt;getOriginalKeys();
    if ($original_keys == 'field_facet_filter')) {
        $query-&gt;keys(NULL);
    }
}


2) If Apache Solr Search module is use

function hook_apachesolr_query_prepare(DrupalSolrQueryInterface $query) {
  ‌‌if ($query-&gt;getParam('q') == 'field_facet_filter') {
    $query-&gt;removeParam('q');
  }
}