Cannot access email section of settings I somehow can't access the email section of settings;
/admin/settings/email

Argument 1 passed to craft\helpers\MailerHelper::createTransportAdapter() must be of the type string, null given, called in ___/vendor/craftcms/cms/src/controllers/SystemSettingsController.php on line 139


Everything is up to date, and I've tried disabling all plugins.

Any tips on how to fix this?

I don't think I previously have added any email settings to the site, so it should have been a clean slate.
Try this in dev or back up first.
Set 'useProjectConfigFile' =&gt; true, in your config/general.php and refresh your Control Panel. This will place a project.yaml file in your config/ folder.
Open that file and look for a portion that looks like this:
email:
  fromEmail: your@email.com
  fromName: Sitename
  transportType: craft\mail\transportadapters\Sendmail

If only your transportType is empty, add craft\mail\transportadapters\Sendmail as above (you'll be able to change that later if needed). If more is missing, set at least what you see above and if you have no email section at all, add it.
Save the file then refresh your Control Panel. It should say Changes to project.yaml must be applied to the loaded project config. Hit the Sync changes button.
Next, check if you can access your mail settings again and if so set 'useProjectConfigFile' back to false.