diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index 7008f6952155..8e88f743d17a 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -1297,6 +1297,27 @@ mozilla::ipc::IPCResult ContentParent::RecvUngrabPointer(
 #endif
 }
 
+static void LogFailedPrincipalValidationInfo(nsIPrincipal* aPrincipal,
+                                             const char* aMethod) {
+  // no need to do the dance if logging is disabled
+  if (MOZ_LOG_TEST(ContentParent::GetLog(), LogLevel::Error)) {
+    nsAutoCString spec;
+    if (!aPrincipal) {
+      spec.AssignLiteral("NullPtr");
+    } else if (aPrincipal->IsSystemPrincipal()) {
+      spec.AssignLiteral("SystemPrincipal");
+    } else if (aPrincipal->GetIsExpandedPrincipal()) {
+      spec.AssignLiteral("ExpandedPrincipal");
+    } else if (aPrincipal->GetIsContentPrincipal()) {
+      aPrincipal->GetSpec(spec);
+    }
+
+    MOZ_LOG(ContentParent::GetLog(), LogLevel::Error,
+            ("  Receiving unexpected Principal (%s) within %s", spec.get(),
+             aMethod));
+  }
+}
+
 bool ContentParent::ValidatePrincipal(
     nsIPrincipal* aPrincipal,
     const EnumSet<ValidatePrincipalOptions>& aOptions) {
@@ -1397,7 +1418,7 @@ mozilla::ipc::IPCResult ContentParent::RecvRemovePermission(
     const IPC::Principal& aPrincipal, const nsCString& aPermissionType,
     nsresult* aRv) {
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   *aRv = Permissions::RemovePermission(aPrincipal, aPermissionType);
   return IPC_OK();
@@ -3249,7 +3270,7 @@ mozilla::ipc::IPCResult ContentParent::RecvSetClipboard(
     const int32_t& aWhichClipboard) {
   if (!ValidatePrincipal(aRequestingPrincipal,
                          {ValidatePrincipalOptions::AllowNullPtr})) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aRequestingPrincipal, __func__);
   }
 
   nsresult rv;
@@ -4481,7 +4502,7 @@ mozilla::ipc::IPCResult ContentParent::RecvCloseAlert(const nsString& aName) {
 mozilla::ipc::IPCResult ContentParent::RecvDisableNotifications(
     const IPC::Principal& aPrincipal) {
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   Unused << Notification::RemovePermission(aPrincipal);
   return IPC_OK();
@@ -4490,7 +4511,7 @@ mozilla::ipc::IPCResult ContentParent::RecvDisableNotifications(
 mozilla::ipc::IPCResult ContentParent::RecvOpenNotificationSettings(
     const IPC::Principal& aPrincipal) {
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   Unused << Notification::OpenSettings(aPrincipal);
   return IPC_OK();
@@ -5040,7 +5061,7 @@ bool ContentParent::DeallocPWebrtcGlobalParent(PWebrtcGlobalParent* aActor) {
 mozilla::ipc::IPCResult ContentParent::RecvSetOfflinePermission(
     const Principal& aPrincipal) {
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   nsCOMPtr<nsIOfflineCacheUpdateService> updateService =
       components::OfflineCacheUpdate::Service();
@@ -5378,7 +5399,7 @@ mozilla::ipc::IPCResult ContentParent::RecvCreateWindow(
     CreateWindowResolver&& aResolve) {
   if (!ValidatePrincipal(aTriggeringPrincipal,
                          {ValidatePrincipalOptions::AllowSystem})) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aTriggeringPrincipal, __func__);
   }
 
   nsresult rv = NS_OK;
@@ -5694,7 +5715,7 @@ mozilla::ipc::IPCResult ContentParent::RecvNotifyPushObservers(
     const nsCString& aScope, const IPC::Principal& aPrincipal,
     const nsString& aMessageId) {
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   PushMessageDispatcher dispatcher(aScope, aPrincipal, aMessageId, Nothing());
   Unused << NS_WARN_IF(NS_FAILED(dispatcher.NotifyObserversAndWorkers()));
@@ -5705,7 +5726,7 @@ mozilla::ipc::IPCResult ContentParent::RecvNotifyPushObserversWithData(
     const nsCString& aScope, const IPC::Principal& aPrincipal,
     const nsString& aMessageId, nsTArray<uint8_t>&& aData) {
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   PushMessageDispatcher dispatcher(aScope, aPrincipal, aMessageId,
                                    Some(std::move(aData)));
@@ -5717,7 +5738,7 @@ mozilla::ipc::IPCResult
 ContentParent::RecvNotifyPushSubscriptionChangeObservers(
     const nsCString& aScope, const IPC::Principal& aPrincipal) {
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   PushSubscriptionChangeDispatcher dispatcher(aScope, aPrincipal);
   Unused << NS_WARN_IF(NS_FAILED(dispatcher.NotifyObserversAndWorkers()));
@@ -5728,7 +5749,7 @@ mozilla::ipc::IPCResult ContentParent::RecvPushError(
     const nsCString& aScope, const IPC::Principal& aPrincipal,
     const nsString& aMessage, const uint32_t& aFlags) {
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   PushErrorDispatcher dispatcher(aScope, aPrincipal, aMessage, aFlags);
   Unused << NS_WARN_IF(NS_FAILED(dispatcher.NotifyObserversAndWorkers()));
@@ -5739,7 +5760,7 @@ mozilla::ipc::IPCResult
 ContentParent::RecvNotifyPushSubscriptionModifiedObservers(
     const nsCString& aScope, const IPC::Principal& aPrincipal) {
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   PushSubscriptionModifiedDispatcher dispatcher(aScope, aPrincipal);
   Unused << NS_WARN_IF(NS_FAILED(dispatcher.NotifyObservers()));
@@ -5812,7 +5833,7 @@ mozilla::ipc::IPCResult ContentParent::RecvStoreAndBroadcastBlobURLRegistration(
     const nsCString& aURI, const IPCBlob& aBlob, const Principal& aPrincipal,
     const Maybe<nsID>& aAgentClusterId) {
   if (!ValidatePrincipal(aPrincipal, {ValidatePrincipalOptions::AllowSystem})) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   RefPtr<BlobImpl> blobImpl = IPCBlobUtils::Deserialize(aBlob);
   if (NS_WARN_IF(!blobImpl)) {
@@ -5835,7 +5856,7 @@ mozilla::ipc::IPCResult
 ContentParent::RecvUnstoreAndBroadcastBlobURLUnregistration(
     const nsCString& aURI, const Principal& aPrincipal) {
   if (!ValidatePrincipal(aPrincipal, {ValidatePrincipalOptions::AllowSystem})) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   BlobURLProtocolHandler::RemoveDataEntry(aURI, false /* Don't broadcast */);
   BroadcastBlobURLUnregistration(aURI, aPrincipal, this);
@@ -6181,10 +6202,6 @@ PURLClassifierParent* ContentParent::AllocPURLClassifierParent(
 
 mozilla::ipc::IPCResult ContentParent::RecvPURLClassifierConstructor(
     PURLClassifierParent* aActor, const Principal& aPrincipal, bool* aSuccess) {
-  if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
-  }
-
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(aActor);
   *aSuccess = false;
@@ -6196,7 +6213,7 @@ mozilla::ipc::IPCResult ContentParent::RecvPURLClassifierConstructor(
     return IPC_OK();
   }
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   return actor->StartClassify(principal, aSuccess);
 }
@@ -6365,7 +6382,7 @@ ContentParent::RecvAutomaticStorageAccessPermissionCanBeGranted(
     const Principal& aPrincipal,
     AutomaticStorageAccessPermissionCanBeGrantedResolver&& aResolver) {
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   aResolver(Document::AutomaticStorageAccessPermissionCanBeGranted(aPrincipal));
   return IPC_OK();
@@ -6439,7 +6456,7 @@ mozilla::ipc::IPCResult ContentParent::RecvCompleteAllowAccessFor(
 mozilla::ipc::IPCResult ContentParent::RecvStoreUserInteractionAsPermission(
     const Principal& aPrincipal) {
   if (!ValidatePrincipal(aPrincipal)) {
-    return IPC_FAIL(this, "receiving unexpected principal");
+    LogFailedPrincipalValidationInfo(aPrincipal, __func__);
   }
   ContentBlockingUserInteraction::Observe(aPrincipal);
   return IPC_OK();