there couple of places you should check.
1) okta developer dashboard. when we create an application there, the default value of Login redirect URIs is "http://localhost:8080/authorization-code/callback". if your web site's call back url is different from it, you have to update it to here. for example, my call back url is "http://localhost:8001/Home/Authenticate".
2) if you have a config value in your web site. make sure the config value is updated to the same URL, my case is in ASP.NET web.config => appSettings, update the value of "okta:RedirectUri" to "http://localhost:8001/Home/Authenticate"
3) if you are using okta sign-in widget and you want to redirect to your web page, you need to ensure the JavaScript, when you create OktaSignIn object, did you specify redirectUri? if so, make sure you have the right Url there. more details about the widget click here
var signIn = new OktaSignIn({
baseUrl: 'https://dev-*******.okta.com',
clientId: '${clientId}',
redirectUri: '${redirectUri configured in OIDC app}',
authParams: {
issuer: 'default',
responseType: ['id_token','token'],
display: 'page'
}
});