diff --git a/router/router.go b/router/router.go
index 5d160687b79..e8eb12db734 100644
--- a/router/router.go
+++ b/router/router.go
@@ -220,9 +220,9 @@ func New(cfg *config.Configuration, rateConvertor *currency.RateConverter) (r *R
 		return nil, err
 	}
 
-	syncersByBidder, err := usersync.BuildSyncers(cfg, bidderInfos)
-	if err != nil {
-		return nil, err
+	syncersByBidder, errs := usersync.BuildSyncers(cfg, bidderInfos)
+	if errsFiltered := filterSyncerErrors(errs); len(errsFiltered) > 0 {
+		return nil, errortypes.NewAggregateError("user sync", errsFiltered)
 	}
 
 	syncerKeys := make([]string, 0, len(syncersByBidder))
@@ -341,7 +341,7 @@ func applyBidderInfoConfigOverrides(bidderInfos config.BidderInfos, adaptersCfg
 			// the new config.
 			if adapterCfg.UserSyncURL != "" {
 				if bidderInfo.Syncer == nil {
-					return fmt.Errorf("failed to apply legacy usersync_url setting for bidder %s, bidder does not define a user sync or is disabled", bidderName)
+					return fmt.Errorf("adapters.%s.usersync_url cannot be applied, bidder does not define a user sync", strings.ToLower(bidderName))
 				}
 
 				endpointsCount := 0
@@ -355,17 +355,17 @@ func applyBidderInfoConfigOverrides(bidderInfos config.BidderInfos, adaptersCfg
 				}
 
 				if endpointsCount == 0 {
-					return fmt.Errorf("failed to apply legacy usersync_url setting for bidder %s, bidder does not define user sync endpoints", bidderName)
+					return fmt.Errorf("adapters.%s.usersync_url cannot be applied, bidder does not define user sync endpoints", strings.ToLower(bidderName))
 				}
 
 				// if the bidder defines both an iframe and redirect endpoint, we can't be sure which config value to
 				// override, and  it wouldn't be both. this is a fatal configuration error.
 				if endpointsCount > 1 {
-					return fmt.Errorf("failed to apply legacy usersync_url setting for bidder %s, bidder defines multiple user sync endpoints", bidderName)
+					return fmt.Errorf("adapters.%s.usersync_url cannot be applied, bidder defines multiple user sync endpoints", strings.ToLower(bidderName))
 				}
 
 				// provide a warning that this compatibility layer is temporary
-				glog.Warningf("legacy usersync_url setting for bidder %s will be removed in a future version of Prebid Server. please update to the latest user sync config values", bidderName)
+				glog.Warningf("adapters.%s.usersync_url is deprecated and will be removed in a future version, please update to the latest user sync config values", strings.ToLower(bidderName))
 			}
 
 			bidderInfos[bidderName] = bidderInfo
@@ -374,6 +374,22 @@ func applyBidderInfoConfigOverrides(bidderInfos config.BidderInfos, adaptersCfg
 	return nil
 }
 
+func filterSyncerErrors(errs []error) []error {
+	var fatalErrors []error
+
+	for _, err := range errs {
+		syncerBuildErr, ok := err.(usersync.SyncerBuildError)
+		if ok && syncerBuildErr.Err == usersync.ErrSyncerURLRequired {
+			bidderName := strings.ToLower(syncerBuildErr.Bidder)
+			glog.Warningf("bidder %s supports user syncing but has endpoints with no default url, no syncs will be performed with %s.", bidderName, bidderName)
+		} else {
+			fatalErrors = append(fatalErrors, err)
+		}
+	}
+
+	return fatalErrors
+}
+
 // Fixes #648
 //
 // These CORS options pose a security risk... but it's a calculated one.
diff --git a/router/router_test.go b/router/router_test.go
index ec7ab43e946..f3a167967ce 100644
--- a/router/router_test.go
+++ b/router/router_test.go
@@ -2,6 +2,7 @@ package router
 
 import (
 	"encoding/json"
+	"errors"
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
@@ -9,7 +10,9 @@ import (
 	"testing"
 
 	"github.com/prebid/prebid-server/config"
+	"github.com/prebid/prebid-server/errortypes"
 	"github.com/prebid/prebid-server/openrtb_ext"
+	"github.com/prebid/prebid-server/usersync"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -104,19 +107,19 @@ func TestApplyBidderInfoConfigOverrides(t *testing.T) {
 			description:      "UserSyncURL Override Syncer Not Defined",
 			givenBidderInfos: config.BidderInfos{"a": {}},
 			givenAdaptersCfg: map[string]config.Adapter{"a": {UserSyncURL: "override"}},
-			expectedError:    "failed to apply legacy usersync_url setting for bidder a, bidder does not define a user sync or is disabled",
+			expectedError:    "adapters.a.usersync_url cannot be applied, bidder does not define a user sync",
 		},
 		{
 			description:      "UserSyncURL Override Syncer Endpoints Not Defined",
 			givenBidderInfos: config.BidderInfos{"a": {Syncer: &config.Syncer{}}},
 			givenAdaptersCfg: map[string]config.Adapter{"a": {UserSyncURL: "override"}},
-			expectedError:    "failed to apply legacy usersync_url setting for bidder a, bidder does not define user sync endpoints",
+			expectedError:    "adapters.a.usersync_url cannot be applied, bidder does not define user sync endpoints",
 		},
 		{
 			description:      "UserSyncURL Override Ambiguous",
 			givenBidderInfos: config.BidderInfos{"a": {Syncer: &config.Syncer{IFrame: &config.SyncerEndpoint{URL: "originalIFrame"}, Redirect: &config.SyncerEndpoint{URL: "originalRedirect"}}}},
 			givenAdaptersCfg: map[string]config.Adapter{"a": {UserSyncURL: "override"}},
-			expectedError:    "failed to apply legacy usersync_url setting for bidder a, bidder defines multiple user sync endpoints",
+			expectedError:    "adapters.a.usersync_url cannot be applied, bidder defines multiple user sync endpoints",
 		},
 	}
 
@@ -131,6 +134,50 @@ func TestApplyBidderInfoConfigOverrides(t *testing.T) {
 	}
 }
 
+func TestFilterSyncerErrors(t *testing.T) {
+	fatalErrorA := errors.New("errorA")
+	fatalErrorB := &errortypes.BadInput{Message: "errorB"}
+	buildErrorURLRequired := usersync.SyncerBuildError{Bidder: "anyBidder", SyncerKey: "anyKey", Err: usersync.ErrSyncerURLRequired}
+	buildErrorOther := usersync.SyncerBuildError{Bidder: "anyBidder", SyncerKey: "anyKey", Err: usersync.ErrSyncerKeyRequired}
+
+	var testCases = []struct {
+		description    string
+		givenErrors    []error
+		expectedErrors []error
+	}{
+		{
+			description:    "Nil",
+			givenErrors:    nil,
+			expectedErrors: nil,
+		},
+		{
+			description:    "Empty",
+			givenErrors:    []error{},
+			expectedErrors: nil,
+		},
+		{
+			description:    "One - Not Filtered",
+			givenErrors:    []error{fatalErrorA},
+			expectedErrors: []error{fatalErrorA},
+		},
+		{
+			description:    "One - Filtered",
+			givenErrors:    []error{buildErrorURLRequired},
+			expectedErrors: nil,
+		},
+		{
+			description:    "Many - Mixed",
+			givenErrors:    []error{fatalErrorA, fatalErrorB, buildErrorURLRequired, buildErrorOther},
+			expectedErrors: []error{fatalErrorA, fatalErrorB, buildErrorOther},
+		},
+	}
+
+	for _, test := range testCases {
+		filteredErrs := filterSyncerErrors(test.givenErrors)
+		assert.Equal(t, test.expectedErrors, filteredErrs, test.description)
+	}
+}
+
 // Prevents #648
 func TestCORSSupport(t *testing.T) {
 	const origin = "https://publisher-domain.com"
diff --git a/static/bidder-info/adocean.yaml b/static/bidder-info/adocean.yaml
index 6374d752c34..e53dcc32a5f 100644
--- a/static/bidder-info/adocean.yaml
+++ b/static/bidder-info/adocean.yaml
@@ -8,3 +8,8 @@ capabilities:
   site:
     mediaTypes:
       - banner
+userSync:
+  redirect:
+    # adocean supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/adtarget.yaml b/static/bidder-info/adtarget.yaml
index cc064b9ca6b..694ed139095 100644
--- a/static/bidder-info/adtarget.yaml
+++ b/static/bidder-info/adtarget.yaml
@@ -10,3 +10,8 @@ capabilities:
     mediaTypes:
       - banner
       - video
+userSync:
+  iframe:
+    # adtarget supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/adtelligent.yaml b/static/bidder-info/adtelligent.yaml
index 30f55ea912e..6cb2c514743 100644
--- a/static/bidder-info/adtelligent.yaml
+++ b/static/bidder-info/adtelligent.yaml
@@ -10,3 +10,8 @@ capabilities:
     mediaTypes:
       - banner
       - video
+userSync:
+  iframe:
+    # adtelligent supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/adxcg.yaml b/static/bidder-info/adxcg.yaml
index e5535ae7258..d2b15524310 100644
--- a/static/bidder-info/adxcg.yaml
+++ b/static/bidder-info/adxcg.yaml
@@ -11,3 +11,8 @@ capabilities:
       - banner
       - video
       - native
+userSync:
+  redirect:
+    # adxcg supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/audienceNetwork.yaml b/static/bidder-info/audienceNetwork.yaml
index 324e5c6dff8..451959f7ec5 100644
--- a/static/bidder-info/audienceNetwork.yaml
+++ b/static/bidder-info/audienceNetwork.yaml
@@ -6,3 +6,8 @@ capabilities:
       - banner
       - video
       - native
+userSync:
+  redirect:
+    # facebook's audience network supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/bmtm.yaml b/static/bidder-info/bmtm.yaml
index c13bf17db73..526e7d857af 100644
--- a/static/bidder-info/bmtm.yaml
+++ b/static/bidder-info/bmtm.yaml
@@ -6,3 +6,8 @@ capabilities:
     mediaTypes:
       - banner
       - video
+userSync:
+  redirect:
+    # bmtm supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/criteo.yaml b/static/bidder-info/criteo.yaml
index bfa098ba39d..0898e5938ec 100644
--- a/static/bidder-info/criteo.yaml
+++ b/static/bidder-info/criteo.yaml
@@ -7,4 +7,9 @@ capabilities:
       - banner
   site:
     mediaTypes:
-      - banner
\ No newline at end of file
+      - banner
+userSync:
+  redirect:
+    # criteo supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/dmx.yaml b/static/bidder-info/dmx.yaml
index d29d699daeb..04e3612512b 100644
--- a/static/bidder-info/dmx.yaml
+++ b/static/bidder-info/dmx.yaml
@@ -10,3 +10,8 @@ capabilities:
     mediaTypes:
       - banner
       - video
+userSync:
+  redirect:
+    # dmx supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/gamma.yaml b/static/bidder-info/gamma.yaml
index aedaf2cf749..ef230dc30c0 100644
--- a/static/bidder-info/gamma.yaml
+++ b/static/bidder-info/gamma.yaml
@@ -5,3 +5,8 @@ capabilities:
     mediaTypes:
       - banner
       - video
+userSync:
+  iframe:
+    # gamma supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/invibes.yaml b/static/bidder-info/invibes.yaml
index 45184fb9f65..1da3c05ffbe 100644
--- a/static/bidder-info/invibes.yaml
+++ b/static/bidder-info/invibes.yaml
@@ -5,3 +5,8 @@ capabilities:
   site:
     mediaTypes:
       - banner
+userSync:
+  iframe:
+    # invibes supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/lockerdome.yaml b/static/bidder-info/lockerdome.yaml
index eebf3b87841..38e3e346be7 100644
--- a/static/bidder-info/lockerdome.yaml
+++ b/static/bidder-info/lockerdome.yaml
@@ -7,10 +7,12 @@ capabilities:
   site:
     mediaTypes:
       - banner
-# lockerdome requires a platform id for their user sync process. replace <<PlatformID>>
-# in the url below and uncomment the userSync section to enable.
-#
-#userSync:
-#  redirect:
-#    url: "https://lockerdome.com/usync/prebidserver?pid=<<PlatformID>>&gdpr={{.GDPR}}&gdpr_consent={{.GDPRConsent}}&us_privacy={{.USPrivacy}}&redirect={{.RedirectURL}}"
-#    userMacro: "{{uid}}"
+userSync:
+  redirect:
+    # lockerdome supports user syncing, but requires a platform id to be configured by
+    # the host. remove the empty url, replace <<PlatformID>> with the value provided, and
+    # uncomment to enable.
+    #
+    # url: "https://lockerdome.com/usync/prebidserver?pid=<<PlatformID>>&gdpr={{.GDPR}}&gdpr_consent={{.GDPRConsent}}&us_privacy={{.USPrivacy}}&redirect={{.RedirectURL}}"
+    url: ""
+    userMacro: "{{uid}}"
diff --git a/static/bidder-info/mediafuse.yaml b/static/bidder-info/mediafuse.yaml
index 98611402905..5e2cedc7932 100644
--- a/static/bidder-info/mediafuse.yaml
+++ b/static/bidder-info/mediafuse.yaml
@@ -10,3 +10,8 @@ capabilities:
     mediaTypes:
       - banner
       - video
+userSync:
+  iframe:
+    # mediafuse supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/rtbhouse.yaml b/static/bidder-info/rtbhouse.yaml
index 12744fdc75e..58196af4c3f 100644
--- a/static/bidder-info/rtbhouse.yaml
+++ b/static/bidder-info/rtbhouse.yaml
@@ -5,3 +5,8 @@ capabilities:
   site:
     mediaTypes:
       - banner
+userSync:
+  redirect:
+    # rtbhouse supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/rubicon.yaml b/static/bidder-info/rubicon.yaml
index 0f19ddb9627..351918ca3cd 100644
--- a/static/bidder-info/rubicon.yaml
+++ b/static/bidder-info/rubicon.yaml
@@ -9,3 +9,8 @@ capabilities:
     mediaTypes:
       - banner
       - video
+userSync:
+  redirect:
+    # rubicon supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/smarthub.yaml b/static/bidder-info/smarthub.yaml
index bfee9490840..32a7a1d0c40 100644
--- a/static/bidder-info/smarthub.yaml
+++ b/static/bidder-info/smarthub.yaml
@@ -11,3 +11,8 @@ capabilities:
       - banner
       - video
       - native
+userSync:
+  redirect:
+    # smarthub supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/synacormedia.yaml b/static/bidder-info/synacormedia.yaml
index 14a4bcd1244..774ba35720f 100644
--- a/static/bidder-info/synacormedia.yaml
+++ b/static/bidder-info/synacormedia.yaml
@@ -13,3 +13,8 @@ userSync:
   iframe:
     url: "https://sync.technoratimedia.com/services?srv=cs&pid=70&cb={{.RedirectURL}}"
     userMacro: "[USER_ID]"
+userSync:
+  iframe:
+    # synacormedia supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/verizonmedia.yaml b/static/bidder-info/verizonmedia.yaml
index 0b4642fcb6a..f629c5f7bf5 100644
--- a/static/bidder-info/verizonmedia.yaml
+++ b/static/bidder-info/verizonmedia.yaml
@@ -8,3 +8,8 @@ capabilities:
   site:
     mediaTypes:
       - banner
+userSync:
+  redirect:
+    # verizonmedia supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/viewdeos.yaml b/static/bidder-info/viewdeos.yaml
index 9483e281de0..3ce7f9cf26a 100644
--- a/static/bidder-info/viewdeos.yaml
+++ b/static/bidder-info/viewdeos.yaml
@@ -10,3 +10,8 @@ capabilities:
     mediaTypes:
       - banner
       - video
+userSync:
+  redirect:
+    # viewdeos supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/static/bidder-info/vrtcal.yaml b/static/bidder-info/vrtcal.yaml
index fcf9294adcb..e86513f38e1 100644
--- a/static/bidder-info/vrtcal.yaml
+++ b/static/bidder-info/vrtcal.yaml
@@ -4,3 +4,8 @@ capabilities:
   app:
     mediaTypes:
       - banner
+userSync:
+  redirect:
+    # vrtcal supports user syncing, but requires configuration by the host. paste the
+    # url provided by the bidder below to enable.
+    url: ""
\ No newline at end of file
diff --git a/usersync/syncer.go b/usersync/syncer.go
index bd23e621eae..220a0b5fa68 100644
--- a/usersync/syncer.go
+++ b/usersync/syncer.go
@@ -58,19 +58,26 @@ const (
 	setuidSyncTypeRedirect = "i" // i = image response
 )
 
-var errEndpointRequired = errors.New("at least one endpoint (iframe and/or redirect) is required")
-var errKeyRequired = errors.New("key is required")
-var errDefaultSyncTypeRequired = errors.New("default sync type is required when more then one sync endpoint is configured")
+var ErrSyncerEndpointRequired = errors.New("at least one endpoint (iframe and/or redirect) is required")
+var ErrSyncerURLRequired = errors.New("each endpoint defined (iframe and/or redirect) must specify a url")
+var ErrSyncerKeyRequired = errors.New("key is required")
+var ErrSyncerDefaultSyncTypeRequired = errors.New("default sync type is required when more then one sync endpoint is configured")
 
 // NewSyncer creates a new Syncer from the provided configuration, or an error if macro substition
 // fails or an endpoint url is invalid.
 func NewSyncer(hostConfig config.UserSync, syncerConfig config.Syncer) (Syncer, error) {
 	if syncerConfig.Key == "" {
-		return nil, errKeyRequired
+		return nil, ErrSyncerKeyRequired
 	}
 
 	if syncerConfig.IFrame == nil && syncerConfig.Redirect == nil {
-		return nil, errEndpointRequired
+		return nil, ErrSyncerEndpointRequired
+	}
+
+	// bidders may define an endpoint but leave the url empty as a way to communicate with the host
+	// that they support this endpoint, but don't provide a default value.
+	if (syncerConfig.IFrame != nil && syncerConfig.IFrame.URL == "") || (syncerConfig.Redirect != nil && syncerConfig.Redirect.URL == "") {
+		return nil, ErrSyncerURLRequired
 	}
 
 	syncer := standardSyncer{
@@ -112,7 +119,7 @@ func NewSyncer(hostConfig config.UserSync, syncerConfig config.Syncer) (Syncer,
 func resolveDefaultSyncType(syncerConfig config.Syncer) (SyncType, error) {
 	if syncerConfig.Default == "" {
 		if syncerConfig.IFrame != nil && syncerConfig.Redirect != nil {
-			return SyncTypeUnknown, errDefaultSyncTypeRequired
+			return SyncTypeUnknown, ErrSyncerDefaultSyncTypeRequired
 		} else if syncerConfig.IFrame != nil {
 			return SyncTypeIFrame, nil
 		} else {
diff --git a/usersync/syncer_test.go b/usersync/syncer_test.go
index 2f4e3203905..05fc8506623 100644
--- a/usersync/syncer_test.go
+++ b/usersync/syncer_test.go
@@ -17,6 +17,7 @@ func TestNewSyncer(t *testing.T) {
 		supportCORS      = true
 		hostConfig       = config.UserSync{ExternalURL: "http://host.com", RedirectURL: "{{.ExternalURL}}/host"}
 		macroValues      = macros.UserSyncTemplateParams{GDPR: "A", GDPRConsent: "B", USPrivacy: "C"}
+		emptyConfig      = &config.SyncerEndpoint{}
 		iframeConfig     = &config.SyncerEndpoint{URL: "https://bidder.com/iframe?redirect={{.RedirectURL}}"}
 		redirectConfig   = &config.SyncerEndpoint{URL: "https://bidder.com/redirect?redirect={{.RedirectURL}}"}
 		errParseConfig   = &config.SyncerEndpoint{URL: "{{malformed}}"}
@@ -50,6 +51,14 @@ func TestNewSyncer(t *testing.T) {
 			givenRedirectConfig: nil,
 			expectedError:       "at least one endpoint (iframe and/or redirect) is required",
 		},
+		{
+			description:         "Missing URLs - IFrame & Redirect",
+			givenKey:            "a",
+			givenDefault:        "redirect",
+			givenIFrameConfig:   emptyConfig,
+			givenRedirectConfig: emptyConfig,
+			expectedError:       "each endpoint defined (iframe and/or redirect) must specify a url",
+		},
 		{
 			description:         "Resolve Default Sync Type Error ",
 			givenKey:            "a",
@@ -68,6 +77,14 @@ func TestNewSyncer(t *testing.T) {
 			expectedIFrame:      "https://bidder.com/iframe?redirect=http%3A%2F%2Fhost.com%2Fhost",
 			expectedRedirect:    "https://bidder.com/redirect?redirect=http%3A%2F%2Fhost.com%2Fhost",
 		},
+		{
+			description:         "IFrame - Missing URL Error",
+			givenKey:            "a",
+			givenDefault:        "iframe",
+			givenIFrameConfig:   emptyConfig,
+			givenRedirectConfig: nil,
+			expectedError:       "each endpoint defined (iframe and/or redirect) must specify a url",
+		},
 		{
 			description:         "IFrame - Parse Error",
 			givenKey:            "a",
@@ -84,6 +101,14 @@ func TestNewSyncer(t *testing.T) {
 			givenRedirectConfig: nil,
 			expectedError:       "iframe composed url: \"notAURL:http%3A%2F%2Fhost.com%2Fhost\" is invalid",
 		},
+		{
+			description:         "Redirect - Missing URL Error",
+			givenKey:            "a",
+			givenDefault:        "redirect",
+			givenIFrameConfig:   nil,
+			givenRedirectConfig: emptyConfig,
+			expectedError:       "each endpoint defined (iframe and/or redirect) must specify a url",
+		},
 		{
 			description:         "Redirect - Parse Error",
 			givenKey:            "a",
diff --git a/usersync/syncersbuilder.go b/usersync/syncersbuilder.go
index bf89b487aa8..96b6b9d219e 100644
--- a/usersync/syncersbuilder.go
+++ b/usersync/syncersbuilder.go
@@ -6,7 +6,6 @@ import (
 	"strings"
 
 	"github.com/prebid/prebid-server/config"
-	"github.com/prebid/prebid-server/errortypes"
 )
 
 type namedSyncerConfig struct {
@@ -14,7 +13,19 @@ type namedSyncerConfig struct {
 	cfg  config.Syncer
 }
 
-func BuildSyncers(hostConfig *config.Configuration, bidderInfos config.BidderInfos) (map[string]Syncer, error) {
+// SyncerBuildError represents an error with building a syncer.
+type SyncerBuildError struct {
+	Bidder    string
+	SyncerKey string
+	Err       error
+}
+
+// Error implements the standard error interface.
+func (e SyncerBuildError) Error() string {
+	return fmt.Sprintf("cannot create syncer for bidder %s with key %s: %v", e.Bidder, e.SyncerKey, e.Err)
+}
+
+func BuildSyncers(hostConfig *config.Configuration, bidderInfos config.BidderInfos) (map[string]Syncer, []error) {
 	// map syncer config by bidder
 	cfgByBidder := make(map[string]config.Syncer, len(bidderInfos))
 	for bidder, cfg := range bidderInfos {
@@ -50,7 +61,11 @@ func BuildSyncers(hostConfig *config.Configuration, bidderInfos config.BidderInf
 
 		syncer, err := NewSyncer(hostUserSyncConfig, primaryCfg.cfg)
 		if err != nil {
-			errs = append(errs, fmt.Errorf("cannot create syncer for bidder %s with key %s. %v", primaryCfg.name, key, err))
+			errs = append(errs, SyncerBuildError{
+				Bidder:    primaryCfg.name,
+				SyncerKey: key,
+				Err:       err,
+			})
 			continue
 		}
 
@@ -60,7 +75,7 @@ func BuildSyncers(hostConfig *config.Configuration, bidderInfos config.BidderInf
 	}
 
 	if len(errs) > 0 {
-		return nil, errortypes.NewAggregateError("user sync", errs)
+		return nil, errs
 	}
 	return syncers, nil
 }
diff --git a/usersync/syncersbuilder_test.go b/usersync/syncersbuilder_test.go
index 29f00b79621..f166c538524 100644
--- a/usersync/syncersbuilder_test.go
+++ b/usersync/syncersbuilder_test.go
@@ -1,7 +1,7 @@
 package usersync
 
 import (
-	"strings"
+	"errors"
 	"testing"
 
 	"github.com/prebid/prebid-server/config"
@@ -9,6 +9,15 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func TestSyncerBuildError(t *testing.T) {
+	err := SyncerBuildError{
+		Bidder:    "anyBidder",
+		SyncerKey: "anyKey",
+		Err:       errors.New("anyError"),
+	}
+	assert.Equal(t, err.Error(), "cannot create syncer for bidder anyBidder with key anyKey: anyError")
+}
+
 func TestBuildSyncers(t *testing.T) {
 	var (
 		hostConfig              = config.Configuration{ExternalURL: "http://host.com", UserSync: config.UserSync{RedirectURL: "{{.ExternalURL}}/{{.SyncerKey}}/host"}}
@@ -26,12 +35,11 @@ func TestBuildSyncers(t *testing.T) {
 	// in these tests. Look carefully at the end of the expected iframe urls to see the syncer key.
 
 	testCases := []struct {
-		description           string
-		givenConfig           config.Configuration
-		givenBidderInfos      config.BidderInfos
-		expectedIFramesURLs   map[string]string
-		expectedErrorHeader   string
-		expectedErrorSegments []string
+		description         string
+		givenConfig         config.Configuration
+		givenBidderInfos    config.BidderInfos
+		expectedIFramesURLs map[string]string
+		expectedErrors      []string
 	}{
 		{
 			description:      "One",
@@ -50,12 +58,11 @@ func TestBuildSyncers(t *testing.T) {
 			},
 		},
 		{
-			description:         "One - Syncer Error",
-			givenConfig:         hostConfig,
-			givenBidderInfos:    map[string]config.BidderInfo{"bidder1": infoKeyAError},
-			expectedErrorHeader: "user sync (1 error)",
-			expectedErrorSegments: []string{
-				"cannot create syncer for bidder bidder1 with key a. default is set to redirect but no redirect endpoint is configured\n",
+			description:      "One - Syncer Error",
+			givenConfig:      hostConfig,
+			givenBidderInfos: map[string]config.BidderInfo{"bidder1": infoKeyAError},
+			expectedErrors: []string{
+				"cannot create syncer for bidder bidder1 with key a: default is set to redirect but no redirect endpoint is configured",
 			},
 		},
 		{
@@ -77,21 +84,27 @@ func TestBuildSyncers(t *testing.T) {
 			},
 		},
 		{
-			description:         "Many - Same Syncers - Many Primaries",
-			givenConfig:         hostConfig,
-			givenBidderInfos:    map[string]config.BidderInfo{"bidder1": infoKeyAPopulated, "bidder2": infoKeyAPopulated},
-			expectedErrorHeader: "user sync (1 error)",
-			expectedErrorSegments: []string{
-				"bidders bidder1, bidder2 define endpoints (iframe and/or redirect) for the same syncer key, but only one bidder is permitted to define endpoints\n",
+			description:      "Many - Same Syncers - Many Primaries - All Populated",
+			givenConfig:      hostConfig,
+			givenBidderInfos: map[string]config.BidderInfo{"bidder1": infoKeyAPopulated, "bidder2": infoKeyAPopulated},
+			expectedErrors: []string{
+				"bidders bidder1, bidder2 define endpoints (iframe and/or redirect) for the same syncer key, but only one bidder is permitted to define endpoints",
+			},
+		},
+		{
+			description:      "Many - Same Syncers - Many Primaries - None Populated",
+			givenConfig:      hostConfig,
+			givenBidderInfos: map[string]config.BidderInfo{"bidder1": infoKeyAEmpty, "bidder2": infoKeyAEmpty},
+			expectedErrors: []string{
+				"bidders bidder1, bidder2 share the same syncer key, but none define endpoints (iframe and/or redirect)",
 			},
 		},
 		{
-			description:         "Many - Sync Error - Bidder Correct",
-			givenConfig:         hostConfig,
-			givenBidderInfos:    map[string]config.BidderInfo{"bidder1": infoKeyAEmpty, "bidder2": infoKeyAError},
-			expectedErrorHeader: "user sync (1 error)",
-			expectedErrorSegments: []string{
-				"cannot create syncer for bidder bidder2 with key a. default is set to redirect but no redirect endpoint is configured\n",
+			description:      "Many - Sync Error - Bidder Correct",
+			givenConfig:      hostConfig,
+			givenBidderInfos: map[string]config.BidderInfo{"bidder1": infoKeyAEmpty, "bidder2": infoKeyAError},
+			expectedErrors: []string{
+				"cannot create syncer for bidder bidder2 with key a: default is set to redirect but no redirect endpoint is configured",
 			},
 		},
 		{
@@ -111,13 +124,12 @@ func TestBuildSyncers(t *testing.T) {
 			},
 		},
 		{
-			description:         "Many - Multiple Errors",
-			givenConfig:         hostConfig,
-			givenBidderInfos:    map[string]config.BidderInfo{"bidder1": infoKeyAError, "bidder2": infoKeyBEmpty},
-			expectedErrorHeader: "user sync (2 errors)",
-			expectedErrorSegments: []string{
-				"cannot create syncer for bidder bidder1 with key a. default is set to redirect but no redirect endpoint is configured\n",
-				"cannot create syncer for bidder bidder2 with key b. at least one endpoint (iframe and/or redirect) is required\n",
+			description:      "Many - Multiple Errors",
+			givenConfig:      hostConfig,
+			givenBidderInfos: map[string]config.BidderInfo{"bidder1": infoKeyAError, "bidder2": infoKeyBEmpty},
+			expectedErrors: []string{
+				"cannot create syncer for bidder bidder1 with key a: default is set to redirect but no redirect endpoint is configured",
+				"cannot create syncer for bidder bidder2 with key b: at least one endpoint (iframe and/or redirect) is required",
 			},
 		},
 		{
@@ -131,10 +143,10 @@ func TestBuildSyncers(t *testing.T) {
 	}
 
 	for _, test := range testCases {
-		result, err := BuildSyncers(&test.givenConfig, test.givenBidderInfos)
+		result, errs := BuildSyncers(&test.givenConfig, test.givenBidderInfos)
 
-		if test.expectedErrorHeader == "" {
-			assert.NoError(t, err, test.description+":err")
+		if len(test.expectedErrors) == 0 {
+			assert.Empty(t, errs, test.description+":err")
 			resultRenderedIFrameURLS := map[string]string{}
 			for k, v := range result {
 				iframeRendered, err := v.GetSync([]SyncType{SyncTypeIFrame}, privacy.Policies{})
@@ -144,11 +156,11 @@ func TestBuildSyncers(t *testing.T) {
 			}
 			assert.Equal(t, test.expectedIFramesURLs, resultRenderedIFrameURLS, test.description+":result")
 		} else {
-			errMessage := err.Error()
-			assert.True(t, strings.HasPrefix(errMessage, test.expectedErrorHeader), test.description+":err")
-			for _, s := range test.expectedErrorSegments {
-				assert.Contains(t, errMessage, s, test.description+":err")
+			errMessages := make([]string, 0, len(errs))
+			for _, e := range errs {
+				errMessages = append(errMessages, e.Error())
 			}
+			assert.ElementsMatch(t, test.expectedErrors, errMessages, test.description+":err")
 			assert.Empty(t, result, test.description+":result")
 		}
 	}