Two problems on my WordPress installation [closed]

Without further info, hard to say. But I would

  • update WP again (even if you already did, just to make sure it is fully updated)
  • change to one of the ‘twenty’ themes (you can do that by temporarily renaming the current theme’s file folder).

Since you state that you disabled all plugins (but not how; I assume that you renamed the plugin folder?) it would seem that the plugins are not the problem. That’s why I suspect the theme – and re-doing the WP update couldn’t hurt.