After update 5.2.1.2 my database is now a text document.

All tables, queries etc are gone. Even backup files no longer open.
What is going on with the update? And can I ever get my database open again?

Please explain exactly what happens when you try to open your Base document. What platform are you using? Do you get any specific error messages when you try to open your Base document? There is a problem with using the JRE (Java runtime environment) solved by using JDK (Java development kit) on some platforms. See Why JDK & not JRE? It is also possible that your database is corrupted though this seems less likely given your backups also don’t work.

See my questions above before I try to post any answer. Is it THIS PROBLEM?