--- a/dom/media/test/test_decode_error.html
+++ b/dom/media/test/test_decode_error.html
@@ -50,17 +50,16 @@ function startTest(test, token) {
 
   v.src = test.name; // implicitly starts a load.
 }
 
 SimpleTest.waitForExplicitFinish();
 SpecialPowers.pushPrefEnv({
   "set": [
     ["media.cache_size", 40000],
-    ["dom.MediaError.message.enabled", true]
   ]
 }, beginTest);
 function beginTest() {
   manager.runTests(gDecodeErrorTests, startTest);
 }
 </script>
 </pre>
 </body>

--- a/dom/webidl/MediaError.webidl
+++ b/dom/webidl/MediaError.webidl
@@ -15,11 +15,10 @@ interface MediaError {
   // Keep these constants in sync with the ones defined in HTMLMediaElement.h
   const unsigned short MEDIA_ERR_ABORTED = 1;
   const unsigned short MEDIA_ERR_NETWORK = 2;
   const unsigned short MEDIA_ERR_DECODE = 3;
   const unsigned short MEDIA_ERR_SRC_NOT_SUPPORTED = 4;
 
   [Constant]
   readonly attribute unsigned short code;
-  [Pref="dom.MediaError.message.enabled"]
   readonly attribute DOMString message;
 };

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -300,23 +300,16 @@ pref("print.shrink-to-fit.scale-limit-pe
 pref("print.use_simplify_page", false);
 
 // Disable support for MathML
 pref("mathml.disabled",    false);
 
 // Enable scale transform for stretchy MathML operators. See bug 414277.
 pref("mathml.scale_stretchy_operators.enabled", true);
 
-// Disable MediaError.message.
-#ifdef RELEASE_OR_BETA
-pref("dom.MediaError.message.enabled", false);
-#else
-pref("dom.MediaError.message.enabled", true);
-#endif
-
 // Enabled on nightly only until we fix mochitest failures.
 #ifdef NIGHTLY_BUILD
 pref("media.dormant-on-pause-timeout-ms", 5000);
 #else
 pref("media.dormant-on-pause-timeout-ms", -1);
 #endif
 
 // Media cache size in kilobytes