[keycloak-user] "Invalid parameter: redirect_uri"

I am using Keycloak with the apiman API manager. Both are on AWS and are behind Elastic Load Balancers (Keycloak is clustered using JDBC_PING). When I request the apiman admin UI page (https://[apimanLoadBalancer]/apimanui), I get redirected to the following URL: https://[KeycloakLoadBalancer]/auth/realms/apiman/protocol/openid-connect... Keycloak then displays the error "We're Sorry... Invalid parameter: redirect_uri" In the Keycloak log I see: DEBUG [org.keycloak.protocol.oidc.utils.RedirectUtils] (default task-7) replacing relative valid redirect with: https://[KeycloakLoadBalancer]/apimanui/* WARN [org.keycloak.events] (default task-7) type=LOGIN_ERROR, realmId=apiman, clientId=apimanui, userId=null, ipAddress=[IP], error=invalid_redirect_uri, response_type=code, redirect_uri=https://[apimanLoadBalancer]/apimanui/index.html, response_mode=query This looks to me as though Keycloak thinks that the redirect URI is a relative path. I also notice that the query string parameters for redirect_uri are not URL encoded by apiman. Would this be the source of the problem?