error=redirect_uri_mismatch Oauth2

Question

I having trouble to create the Refresh Token.

I want to give it to a third party, So it can use it to get an access token and send us data using an exposing web service that I created.

I tried to do the following steps :

1. I created a Connected App.

2. I gave the right OAuth Scopes.

3. Defined a Callback URL.

4. Open a web browser with the follwoing URL :

https://test.salesforce.com/services/oauth2/authorize?response_type=code&client_id=3MVG9llQY5kM..... &​redirect_uri=https://mySandbox.cs108.my.salesforce.com/services/oauth2/authorize

5. Got the mismatch Error :

error=redirect_uri_mismatch&error_description=redirect_uri%20must%20match%20configuration

The Url that gave the mismatch is :

https://test.salesforce.com/services/oauth2/authorize?response_type=code&client_id=3MVG9llQY5kM9....&?redirect_uri=https://mySandbox.cs108.my.salesforce.com/services/oauth2/authorize

Inside my connected App - the Callback URL is exactly the same as the requested URI + I waited 24 hours and not just 10 min for the connected App to be available.

I also tried to add the scope param as : scope=refresh_token , but it give me the same error.

I also tried to do it from my domain since it enabled - but same response. The prevent "test.salesforce" is not checked anyway.

What am I doing wrong?

Thanks!