ConnectionTimeOut in AD B2C Rest API call to get Access Token - azure-ad-b2c

Question

I want to generate access token as the output claim in the below technical profile. I am connecting to a mulesoft api endpoint(https://example.com/ct-oauth2provider-app-xyz/token) which accepts client_id and client_secret in header(client credential flow). But I am getting "ConnectionTimeOut: An exception has occurred." immediately. Any help is greatly appreciated!
I referred : https://learn.microsoft.com/en-us/azure/active-directory-b2c/secure-rest-api?tabs=windows&pivots=b2c-custom-policy#using-oauth2-bearer
<TechnicalProfiles>
<TechnicalProfile Id="API-AcquireAccessToken">
<DisplayName></DisplayName>
<Protocol Name="Proprietary" Handler="Web.TPEngine.Providers.RestfulProvider, Web.TPEngine, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
<Metadata>
<Item Key="ServiceUrl">https://example.com/ct-oauth2provider-app-xyz/token</Item>
<Item Key="AuthenticationType">Basic</Item>
<Item Key="SendClaimsIn">Form</Item>
</Metadata>
<CryptographicKeys>
<Key Id="BasicAuthenticationUsername" StorageReferenceId="B2C_1A_SecureRESTClientId" />
<Key Id="BasicAuthenticationPassword" StorageReferenceId="B2C_1A_SecureRESTClientSecret" />
</CryptographicKeys>
<InputClaims>
<InputClaim ClaimTypeReferenceId="client_id" DefaultValue="lgk" />
<InputClaim ClaimTypeReferenceId="client_secret" DefaultValue="kgf" />
<InputClaim ClaimTypeReferenceId="grant_type" DefaultValue="client_credentials" />
<InputClaim ClaimTypeReferenceId="scope" DefaultValue="https://graph.microsoft.com/.default" />
</InputClaims>
<OutputClaims>
<OutputClaim ClaimTypeReferenceId="bearerToken" PartnerClaimType="access_token" />
</OutputClaims>
<UseTechnicalProfileForSessionManagement ReferenceId="SM-Noop" />
</TechnicalProfile>

Answer 1

For my case, it is because the certificate that bind to your example public url has expired.
The issue solved after I bind a new and updated certificate to my example site.