Azure ADB2C callback url is giving bad request of redirect from OpenID connect

Question

I have a single sign-on solution using Azure ADB2C. I use custom policies.

We have different IDPs and one of them is Auth0. We are connecting to Auth0 using OpenID Connect, but looks like we are having an issue in redirection after user login.

Below is a technical profile for Auth0 OpenId connect in Azure AD B2C custom policies.

<TechnicalProfile Id="Auth0-OID">
            <DisplayName>Auth0</DisplayName>
            <Protocol Name="OpenIdConnect" />
            <Metadata>
                <Item Key="METADATA">https://dev-domain.us.auth0.com/.well-known/openid-configuration</Item>
                <Item Key="authorization_endpoint">https://dev-domain.us.auth0.com/authorize</Item>
                <Item Key="response_types">code</Item>
                <Item Key="response_mode">form_post</Item>
                <Item Key="scope">openid email profile</Item>
                <Item Key="HttpBinding">POST</Item>
                <Item Key="UsePolicyInRedirecturi">0</Item>
                <Item Key="client_id">FqDd**********Yor1hiVlgFk</Item>
             </Metadata>
            <CryptographicKeys>
                <Key Id="client_secret" StorageReferenceId="B2C_1A_Auth0Secret" />
            </CryptographicKeys>                 
            <OutputClaims>
                <!--<OutputClaim ClaimTypeReferenceId="objectId" PartnerClaimType="aud" />-->
                <OutputClaim ClaimTypeReferenceId="email" PartnerClaimType="email" />
                <OutputClaim ClaimTypeReferenceId="givenName" PartnerClaimType="given_name" />
                <OutputClaim ClaimTypeReferenceId="surname" PartnerClaimType="family_name" />
                <OutputClaim ClaimTypeReferenceId="displayName" PartnerClaimType="name" />
                <OutputClaim ClaimTypeReferenceId="identityProvider" DefaultValue="Auth0.com" AlwaysUseDefaultValue="true" />
                <OutputClaim ClaimTypeReferenceId="authenticationSource" DefaultValue="socialIdpAuthentication" />
                <OutputClaim ClaimTypeReferenceId="socialIdpUserId" PartnerClaimType="aud" />
                <OutputClaim ClaimTypeReferenceId="accountEnabled" DefaultValue="True" AlwaysUseDefaultValue="true"/>
            </OutputClaims>
            <OutputClaimsTransformations>
                <OutputClaimsTransformation ReferenceId="CreateRandomUPNUserName" />
                <OutputClaimsTransformation ReferenceId="CreateUserPrincipalName" />
                <OutputClaimsTransformation ReferenceId="CreateAlternativeSecurityId" />
                <OutputClaimsTransformation ReferenceId="CreateSubjectClaimFromAlternativeSecurityId" />
            </OutputClaimsTransformations>
            <UseTechnicalProfileForSessionManagement ReferenceId="SM-SocialLogin" />

After login, it tries to redirect back to the application, but in browser, it just shows a bad request for the below return URL:

https://devdomainb2c.b2clogin.com/devdomainb2c.onmicrosoft.com/oauth2/authresp

Below is the actual error:

What could be the reason for logging in user behind the scenes but not redirecting to the UI?

Appreciate any help.

Devdomain - is not the actual name of the domain. It is used as a placeholder here to hide actual domain.