After Site URL Change, Redirects lead to PHP fatal errors

We changed the URL of our test server and all individual page redirects are causing the site to crash when you visit a link that’s supposed to redirect. Renaming the plugin folder (i.e. disabling plugin) ‘fixes’ the issue of the crashes — but redirects obviously aren’t working then.

We can’t log into admin as well — not sure if this is somehow related.

Thanks in advance! One of our favorite plugins.

https://wordpress.org/plugins/quick-pagepost-redirect-plugin/