1 files changed, 7 insertions, 4 deletions
diff --git a/packages/web-util/src/utils/http-impl.browser.ts b/packages/web-util/src/utils/http-impl.browser.ts
index 974a7d1b8..18140ef13 100644
--- a/packages/web-util/src/utils/http-impl.browser.ts
+++ b/packages/web-util/src/utils/http-impl.browser.ts
@@ -73,10 +73,13 @@ export class BrowserHttpLib implements HttpRequestLibrary {
         ? encodeBody(requestBody)
         : undefined;
 
-    const requestHeadersMap = {
-      ...getDefaultHeaders(requestMethod),
-      ...requestHeader,
-    };
+    const requestHeadersMap = getDefaultHeaders(requestMethod);
+    if (requestHeader) {
+      Object.entries(requestHeader).forEach(([key, value]) => {
+        if (value === undefined) return;
+        requestHeadersMap[key] = value
+      })
+    }
 
     return new Promise<HttpResponse>((resolve, reject) => {
       const myRequest = new XMLHttpRequest();