diff --git a/dom/xslt/xpath/XPathExpression.cpp b/dom/xslt/xpath/XPathExpression.cpp
index c35311a78cb0..201b22a8d630 100644
--- a/dom/xslt/xpath/XPathExpression.cpp
+++ b/dom/xslt/xpath/XPathExpression.cpp
@@ -164,7 +164,10 @@ already_AddRefed<XPathResult> XPathExpression::EvaluateWithContext(
     xpathResult = new XPathResult(&aContextNode);
   }
 
-  aRv = xpathResult->SetExprResult(exprResult, resultType, &aContextNode);
+  xpathResult->SetExprResult(exprResult, resultType, &aContextNode, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
 
   return xpathResult.forget();
 }
diff --git a/dom/xslt/xpath/XPathResult.cpp b/dom/xslt/xpath/XPathResult.cpp
index f07a4b3010b4..c90defd9e110 100644
--- a/dom/xslt/xpath/XPathResult.cpp
+++ b/dom/xslt/xpath/XPathResult.cpp
@@ -79,7 +79,7 @@ void XPathResult::RemoveObserver() {
 
 nsINode* XPathResult::IterateNext(ErrorResult& aRv) {
   if (!isIterator()) {
-    aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
+    aRv.ThrowTypeError(u"Result is not an iterator");
     return nullptr;
   }
 
@@ -88,7 +88,7 @@ nsINode* XPathResult::IterateNext(ErrorResult& aRv) {
   }
 
   if (mInvalidIteratorState) {
-    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    aRv.ThrowInvalidStateError("The document has been mutated since the result was returned");
     return nullptr;
   }
 
@@ -126,9 +126,9 @@ void XPathResult::ContentRemoved(nsIContent* aChild,
   Invalidate(aChild->GetParent());
 }
 
-nsresult XPathResult::SetExprResult(txAExprResult* aExprResult,
-                                    uint16_t aResultType,
-                                    nsINode* aContextNode) {
+void XPathResult::SetExprResult(txAExprResult* aExprResult,
+                                uint16_t aResultType, nsINode* aContextNode,
+                                ErrorResult& aRv) {
   MOZ_ASSERT(aExprResult);
 
   if ((isSnapshot(aResultType) || isIterator(aResultType) ||
@@ -137,7 +137,8 @@ nsresult XPathResult::SetExprResult(txAExprResult* aExprResult,
     // The DOM spec doesn't really say what should happen when reusing an
     // XPathResult and an error is thrown. Let's not touch the XPathResult
     // in that case.
-    return NS_ERROR_DOM_TYPE_ERR;
+    aRv.ThrowTypeError(u"Result type mismatch");
+    return;
   }
 
   mResultType = aResultType;
@@ -184,7 +185,7 @@ nsresult XPathResult::SetExprResult(txAExprResult* aExprResult,
   }
 
   if (!isIterator()) {
-    return NS_OK;
+    return;
   }
 
   mCurrentPos = 0;
@@ -199,8 +200,6 @@ nsresult XPathResult::SetExprResult(txAExprResult* aExprResult,
       mDocument->AddMutationObserver(this);
     }
   }
-
-  return NS_OK;
 }
 
 void XPathResult::Invalidate(const nsIContent* aChangeRoot) {
diff --git a/dom/xslt/xpath/XPathResult.h b/dom/xslt/xpath/XPathResult.h
index 4db8356685be..ba348d276273 100644
--- a/dom/xslt/xpath/XPathResult.h
+++ b/dom/xslt/xpath/XPathResult.h
@@ -31,9 +31,9 @@ class txAExprResult;
 class nsIXPathResult : public nsISupports {
  public:
   NS_DECLARE_STATIC_IID_ACCESSOR(NS_IXPATHRESULT_IID)
-  virtual nsresult SetExprResult(txAExprResult* aExprResult,
-                                 uint16_t aResultType,
-                                 nsINode* aContextNode) = 0;
+  virtual void SetExprResult(txAExprResult* aExprResult, uint16_t aResultType,
+                             nsINode* aContextNode,
+                             mozilla::ErrorResult& aRv) = 0;
   virtual nsresult GetExprResult(txAExprResult** aExprResult) = 0;
   virtual nsresult Clone(nsIXPathResult** aResult) = 0;
 };
@@ -83,7 +83,7 @@ class XPathResult final : public nsIXPathResult,
   uint16_t ResultType() const { return mResultType; }
   double GetNumberValue(ErrorResult& aRv) const {
     if (mResultType != NUMBER_TYPE) {
-      aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
+      aRv.ThrowTypeError(u"Result is not a number");
       return 0;
     }
 
@@ -91,7 +91,7 @@ class XPathResult final : public nsIXPathResult,
   }
   void GetStringValue(nsAString& aStringValue, ErrorResult& aRv) const {
     if (mResultType != STRING_TYPE) {
-      aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
+      aRv.ThrowTypeError(u"Result is not a string");
       return;
     }
 
@@ -99,7 +99,7 @@ class XPathResult final : public nsIXPathResult,
   }
   bool GetBooleanValue(ErrorResult& aRv) const {
     if (mResultType != BOOLEAN_TYPE) {
-      aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
+      aRv.ThrowTypeError(u"Result is not a boolean");
       return false;
     }
 
@@ -107,7 +107,7 @@ class XPathResult final : public nsIXPathResult,
   }
   nsINode* GetSingleNodeValue(ErrorResult& aRv) const {
     if (!isNode()) {
-      aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
+      aRv.ThrowTypeError(u"Result is not a node");
       return nullptr;
     }
 
@@ -118,7 +118,7 @@ class XPathResult final : public nsIXPathResult,
   }
   uint32_t GetSnapshotLength(ErrorResult& aRv) const {
     if (!isSnapshot()) {
-      aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
+      aRv.ThrowTypeError(u"Result is not a snapshot");
       return 0;
     }
 
@@ -127,7 +127,7 @@ class XPathResult final : public nsIXPathResult,
   nsINode* IterateNext(ErrorResult& aRv);
   nsINode* SnapshotItem(uint32_t aIndex, ErrorResult& aRv) const {
     if (!isSnapshot()) {
-      aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
+      aRv.ThrowTypeError(u"Result is not a snapshot");
       return nullptr;
     }
 
@@ -142,8 +142,8 @@ class XPathResult final : public nsIXPathResult,
   NS_DECL_NSIMUTATIONOBSERVER_CONTENTREMOVED
   NS_DECL_NSIMUTATIONOBSERVER_NODEWILLBEDESTROYED
 
-  nsresult SetExprResult(txAExprResult* aExprResult, uint16_t aResultType,
-                         nsINode* aContextNode) override;
+  void SetExprResult(txAExprResult* aExprResult, uint16_t aResultType,
+                     nsINode* aContextNode, ErrorResult& aRv) override;
   nsresult GetExprResult(txAExprResult** aExprResult) override;
   nsresult Clone(nsIXPathResult** aResult) override;
   void RemoveObserver();