Upgrading D8 project - Oembed media throws exception

Please for a bug report we need to understand how you upgraded and the exception message in detail. Those configurations have been part of Drupal since at least 8.1.0 and are part of the module's configuration schema.

Yes I guessed so ... but did not think to save enough information when I was investigating...
What I can tell you is that I come from a project in D 8.9 upgraded to 9.5, and that the error triggered at guzzle level trying to GET the empty url from oembed_providers_url (after a call to Drupal\media\OEmbed\UrlResolver line 133:

    foreach ($this->providers->getAll() as $provider_info) {

If this is not reproducible from a vanilla 8.9 I guess this is specific to my project and the ticket can be closed...
Thanks anyway !