diff --git a/Libraries/Blob/FileReader.js b/Libraries/Blob/FileReader.js
index fc769f8a544a72..15a8b44d0bb522 100644
--- a/Libraries/Blob/FileReader.js
+++ b/Libraries/Blob/FileReader.js
@@ -85,9 +85,15 @@ class FileReader extends (EventTarget(...READER_EVENTS): any) {
     throw new Error('FileReader.readAsArrayBuffer is not implemented');
   }
 
-  readAsDataURL(blob: Blob) {
+  readAsDataURL(blob: ?Blob) {
     this._aborted = false;
 
+    if (blob == null) {
+      throw new TypeError(
+        "Failed to execute 'readAsDataURL' on 'FileReader': parameter 1 is not of type 'Blob'",
+      );
+    }
+
     NativeFileReaderModule.readAsDataURL(blob.data).then(
       (text: string) => {
         if (this._aborted) {
@@ -106,9 +112,15 @@ class FileReader extends (EventTarget(...READER_EVENTS): any) {
     );
   }
 
-  readAsText(blob: Blob, encoding: string = 'UTF-8') {
+  readAsText(blob: ?Blob, encoding: string = 'UTF-8') {
     this._aborted = false;
 
+    if (blob == null) {
+      throw new TypeError(
+        "Failed to execute 'readAsText' on 'FileReader': parameter 1 is not of type 'Blob'",
+      );
+    }
+
     NativeFileReaderModule.readAsText(blob.data, encoding).then(
       (text: string) => {
         if (this._aborted) {
diff --git a/Libraries/Network/XMLHttpRequest.js b/Libraries/Network/XMLHttpRequest.js
index 3f1ebd357e8eaf..32c158e76eb385 100644
--- a/Libraries/Network/XMLHttpRequest.js
+++ b/Libraries/Network/XMLHttpRequest.js
@@ -244,7 +244,7 @@ class XMLHttpRequest extends (EventTarget(...XHR_EVENTS): any) {
         if (typeof this._response === 'object' && this._response) {
           this._cachedResponse = BlobManager.createFromOptions(this._response);
         } else if (this._response === '') {
-          this._cachedResponse = null;
+          this._cachedResponse = BlobManager.createFromParts([]);
         } else {
           throw new Error(`Invalid response for blob: ${this._response}`);
         }