I've just migrated to 8.1.2 and now can't login to the back end.
When I click on the black "Go to the back office" button it takes me to https://oauth.prestashop.com/oauth2/fallbacks/error with the following error message:
The OAuth2 request resulted in an error.
Error: invalid_request
Description: The request is missing a required parameter, includes an invalid parameter value, includes a parameter more than once, or is otherwise malformed. The 'redirect_uri' parameter does not match any of the OAuth 2.0 Client's pre-registered redirect urls.
Hint:
Debug:
You are seeing this page because configuration key urls.error is not set.
If you are an administrator, please read the guide to understand what you need to do. If you are a user, please contact the administrator.
The only way I can login is by clicking "Connect with another method".
Any idea how I can fix this please?