--- a/dom/apps/src/Webapps.jsm
+++ b/dom/apps/src/Webapps.jsm
@@ -2130,17 +2130,17 @@ this.DOMApplicationRegistry = {
     xhr.channel.notificationCallbacks = this.createLoadContext(aData.appId,
                                                                aData.isBrowser);
     xhr.responseType = "json";
 
     xhr.addEventListener("load", (function() {
       if (xhr.status == 200) {
         if (!AppsUtils.checkManifestContentType(app.installOrigin, app.origin,
                                                 xhr.getResponseHeader("content-type"))) {
-          sendError("INVALID_MANIFEST");
+          sendError("INVALID_MANIFEST_CONTENT_TYPE");
           return;
         }
 
         app.manifest = xhr.response;
         if (checkManifest()) {
           app.etag = xhr.getResponseHeader("Etag");
           installApp();
         }
@@ -2230,17 +2230,17 @@ this.DOMApplicationRegistry = {
     xhr.channel.notificationCallbacks = this.createLoadContext(aData.appId,
                                                                aData.isBrowser);
     xhr.responseType = "json";
 
     xhr.addEventListener("load", (function() {
       if (xhr.status == 200) {
         if (!AppsUtils.checkManifestContentType(app.installOrigin, app.origin,
                                                 xhr.getResponseHeader("content-type"))) {
-          sendError("INVALID_MANIFEST");
+          sendError("INVALID_MANIFEST_CONTENT_TYPE");
           return;
         }
 
         app.updateManifest = xhr.response;
         if (!app.updateManifest) {
           sendError("MANIFEST_PARSE_ERROR");
           return;
         }

--- a/dom/apps/tests/test_packaged_app_install.html
+++ b/dom/apps/tests/test_packaged_app_install.html
@@ -105,17 +105,17 @@ var steps = [
     checkAppInstallError("http://notvalidurl", "NETWORK_ERROR");
   },
   function() {
     // Test wrong mini-manifest content type.
     ok(true, "== TEST == Not valid mini-manifest content type");
     var miniManifestURL = PackagedTestHelper.gSJS +
                           "?getManifest=true" +
                           "&noManifestContentType=true";
-    checkAppInstallError(miniManifestURL, "INVALID_MANIFEST");
+    checkAppInstallError(miniManifestURL, "INVALID_MANIFEST_CONTENT_TYPE");
   },
   function() {
     // Test mini-manifest 'size' value is not number. Bug 839435.
     ok(true, "== TEST == Size value is not a number");
     var miniManifestURL = PackagedTestHelper.gSJS +
                           "?getManifest=true" +
                           "&packageSize=\"NotANumber\"";
     checkAppInstallError(miniManifestURL, "INVALID_MANIFEST");

--- a/dom/tests/mochitest/webapps/test_install_errors.xul
+++ b/dom/tests/mochitest/webapps/test_install_errors.xul
@@ -86,17 +86,17 @@ function permissionDenied(next) {
 }
 
 function invalidContent(next) {
   var url = "http://test/chrome/dom/tests/mochitest/webapps/apps/bad_content_type.webapp";
 
   var request = navigator.mozApps.install(url, null);
 
   request.onerror = function onInstallError() {
-    is(this.error.name, "INVALID_MANIFEST", "manifest with bad content type");
+    is(this.error.name, "INVALID_MANIFEST_CONTENT_TYPE", "manifest with bad content type");
     next();
   };
 
   request.onsuccess = function onInstall() {
     ok(false, "manifest with bad content type should fail");
     navigator.mozApps.mgmt.uninstall(this.result).onsuccess = function onUninstall() {
       next();
     };