diff --git a/spec/index.bs b/spec/index.bs
index 8dbee4db..916c0ce7 100644
--- a/spec/index.bs
+++ b/spec/index.bs
@@ -1035,7 +1035,7 @@ To <dfn>fetch the accounts list</dfn> given an {{IdentityProviderAPIConfig}} |co
 {{IdentityProviderConfig}} |provider|, and |globalObject|, run the following steps. This returns an
 {{IdentityProviderAccountList}}.
     1. Let |accountsUrl| be the result of [=computing the manifest URL=] given |provider|,
-        |config|["{{IdentityProviderAPIConfig/accounts_endpoint}}"], and |globalObject|.
+        |config|["{{IdentityProviderAPIConfig/accounts_endpoint}}"], true, and |globalObject|.
     1. If |accountsUrl| is failure, return an empty list.
     1. Let |request| be a new <a spec=fetch for=/>request</a> as follows:
 
@@ -1155,7 +1155,7 @@ To <dfn>fetch an identity assertion</dfn> given a {{USVString}}
     {{IdentityProviderAPIConfig}} |config|, and |globalObject|, run the following steps. This
     returns an {{IdentityCredential}} or an {{IdentityCredentialError}}.
     1. Let |tokenUrl| be the result of [=computing the manifest URL=] given |provider|,
-        |config|["{{IdentityProviderAPIConfig/id_assertion_endpoint}}"], and |globalObject|.
+        |config|["{{IdentityProviderAPIConfig/id_assertion_endpoint}}"], true, and |globalObject|.
     1. If |tokenUrl| is failure:
         1. [=Queue a global task=] on the [=DOM manipulation task source=] given |globalObject| to
             let |error| be a new {{IdentityCredentialError}} given |globalObject|'s
@@ -1220,6 +1220,11 @@ To <dfn>fetch an identity assertion</dfn> given a {{USVString}}
                 "IdentityCredentialError" and return.
             1. [=converted to an IDL value|Convert=] |json| to an {{IdentityCredentialErrorInit}},
                 |errorInit|.
+            1. If |errorInit|.{{IdentityCredentialErrorInit/url}} is present:
+                1. Let |errorUrl| be the result of [=computing the manifest URL=] given |provider|,
+                    |errorInit|.{{IdentityCredentialErrorInit/url}}, false, and |globalObject|.
+                1. If |errorUrl| is failure, set |errorInit|.{{IdentityCredentialErrorInit/url}}
+                    to "".
             1. Let |credential| be a new {{IdentityCredentialError}} given |globalObject|'s
                 [=global object/realm=], "IdentityCredentialError", and |errorInit|. 
     1. Wait for |credential| to be set.
@@ -1280,7 +1285,7 @@ To <dfn noexport>fetch the client metadata</dfn> given an {{IdentityProviderAPIC
 an {{IdentityProviderConfig}} |provider|, run the following steps. This returns an
 {{IdentityProviderClientMetadata}} or failure.
     1. Let |clientMetadataUrl| be the result of [=computing the manifest URL=] given |provider|,
-        |config|["{{IdentityProviderAPIConfig/client_metadata_endpoint}}"], and |globalObject|.
+        |config|["{{IdentityProviderAPIConfig/client_metadata_endpoint}}"], true, and |globalObject|.
     1. If |clientMetadataUrl| is failure, return failure.
     1. Let |request| be a new <a spec=fetch for=/>request</a> as follows: