Solr core authentication check fails

Issue

You may see the error below on `/admin/config/search/search-api/index/acquia_search_index`:

Solr core authentication check fails

Resolution

These steps may be able to fix the error:

• Ensure you are running the latest stable versions of your Search-related modules.
• If using the Search API module, try re-saving the "Server" entry with these steps:
  • Log into your Drupal site as an admin
  • Go to /admin/config/search/search-api
  • Click on the "Server" entry, then try editing and re-saving the form without changes.
  • Check if the connection now works.
• If you are using the Acquia Connector module, try re-connecting your site with these steps:
  • Log into your Drupal site as admin
  • Go to /admin/config/system/acquia-connector/credentials
  • Provide the credentials from cloud.acquia.com. These are located under your Application, under "Product Keys".

If you're still having issues after the above steps, contact Acquia Support.