We were still running CiviCRM 5.22.1 when Wordpress updated to version 5.5, which broke our donation pages because of changes how wordpress redirects. I updated to CiviCRM 5.28.3, but the database upgrade fails - all I see is blank dashboard page an empty pair of brackets and a 'retry' link that does nothing.
Does anyone know how to fix this other than perhaps installing a previous version of Wordpress and CiviCRM 5.22.1 on a development server, importing the current CiviCRM database tables, upgrading to CiviCRM 5.28.3, then importing upgraded CiviCRM database tables to the live server?