Error: The 'post_logout_redirect_uri' parameter must be a Logout redirect URI in the client app settings

Hi,

I am integrating sso authentication okta OIDC with sitecore. Login is working fine. however, getting issue with logout flow.

Id token hint is set correctly
Id token and nonce vales are coming correctly too.
provided same signout url in okta and local configuration

url: https://dev-78138058.okta.com/oauth2/v1/logout?post_logout_redirect_uri=https://devsxa-global-preview.com/identity/postexternallogout?ReturnUrl=/&nonce=4869ed77945a4698950d10ab96c8e581&id_token_hint=eyJraWQiOiI0T0pIRm42eG5YWERGcFViMHNWXzJBUEVTeWNHMllDbW5iVU8zLU5uMmpVIiwiYWxnIjoiUlMyNTYifQ.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.TbhwjmY0qTh7JV1hAUIs7Hol8z1io3-Z_yFhNP7g9t7l4rSUH3J6q30nEl37AaAywSSl5SWGj5ErTP4-HaFgudMzxw7jQW7Qg-rKFf6_JMmsmJF417-nhRwXVCuKPkeJ4ETtFwC3JouzswRim6dWPlZ-nReIHor5MSzkPMrKWjcKyAGPEkAfA4fAC7GhaVma16ERib1UeRFQRf3E5tE_IpJfOZHFJxmuGrgVnYkWPZE21UzXnEVr1hQtJeywnI6s1YxIW55lNZvIHnBBQkqwVS8955jU0tO3isEeik4TkSzIvHf4vU04x7hja-dQXgziXTiXkJhdN_z92DN-BG5R0Q&x-client-SKU=ID_NET461&x-client-ver=5.3.0.0

What URL did you configure within Okta as the post_logout_redirect_uri? Is it exactly the value (note that this is case sensitive) https://devsxa-global-preview.com/identity/postexternallogout?ReturnUrl=/

yep, configured same and it is not working

And it has the trailing / as well? Can you share a screenshot of the app settings within the admin console, just so we can double check?