[Steven Zahm]

@ mattiasa

RE: Why does clicking the export prompt for a database upgrade?

Unknown. The export has no code at all in it that would tell the core of WordPress to trigger its database upgrade process.

What version of WordPress is installed?

Can you please install this plugin and create a temp admin account so I can review:

https://wordpress.org/plugins/temporary-login-without-password/

Reply back, as a private reply, with the token login link.