bad authorization: invalid_request while trying to connect to a gotosocial instance about go-mastodon

[lmas]

Had the same issue. Turned on debug logs for gotosocial and it reported missing "redirect_uri" for the c.Authenticate(..., email, password) call. Can be seen missing it in the source.

Solved it by using auth token workflow instead:

app, err := mastodon.RegisterApp( ...  
...
fmt.Println(app.AuthURI)
fmt.Println("Open this URL in your browser, login, aprove, get token and enter it here:")
var auth string
 _, err = fmt.Scanln(&auth)
...
c := mastodon.NewClient(...
...
err = c.AuthenticateToken(..., authToken, "urn:ietf:wg:oauth:2.0:oob")
...
fmt.Println("Your permanent access token is:")
fmt.Println(c.Config.AccessToken)

Do this once, when registering your application, then store your access token.
Whenever you want to connect a client you simply provide the token and nothing else:

c := mastodon.NewClient(&mastodon.Config{
Server:      "localhost",
AccessToken: "yourstoredtoken",
})