hostedapachesolr.com shut down permanently on October 31, 2022, and its indexes cannot be recovered. If a Drupal tutorial or an old README sent you there, this is how to move the search of your site to an Opensolr Index.
01 · Drupal with Search API, step by step
Create an account
Register at opensolr.com/register. The free plan needs no credit card.
Create an Opensolr Index
Pick a region close to your site and the Solr version your Search API module expects. Steps: create an index.
Connect Drupal
Either install Opensolr Search, the Opensolr module for Drupal, or keep Search API Solr: point its server at the address and login of the index (address and login) and upload the config set Search API generates as one ZIP (upload a ZIP).
Reindex
Run drush search-api:index, or start indexing from the Drupal UI. The index is rebuilt from your site, so nothing has to be exported from the old service.
Verify
Search on your site, then open the index in the Opensolr control panel and watch the requests arrive in Live Query Stream.
02 · Not on Drupal
WordPress has the Opensolr Search plugin. Any other stack talks to the index through the standard Solr HTTP endpoints, and the Opensolr account through the REST API.
03 · What you get
Configuration files edited in the browser: configuration.
Site search with crawling, hybrid search and a hosted search page: Enterprise Site Search.
Query analytics, a live request stream and an error audit: analytics.
Backups on demand or every day, with self-service restore: backup.
HTTP authentication and IP rules on every index: security.