1 files changed, 17 insertions, 2 deletions
diff --git a/app/scripts/lib/extension-store.js b/app/scripts/lib/extension-store.js
index a8b730a65..dd0f82f36 100644
--- a/app/scripts/lib/extension-store.js
+++ b/app/scripts/lib/extension-store.js
@@ -1,11 +1,24 @@
 const extension = require('extensionizer')
 
 const KEYS_TO_SYNC = ['KeyringController', 'PreferencesController']
+const FIREFOX_SYNC_DISABLED_MESSAGE = 'Please set webextensions.storage.sync.enabled to true in about:config'
+
+const handleDisabledSyncAndResolve = (resolve, toResolve) => {
+  // Firefox 52 has sync available on extension.storage, but it is disabled by default
+  const lastError = extension.runtime.lastError
+  if (lastError && lastError.message.includes(FIREFOX_SYNC_DISABLED_MESSAGE)) {
+    resolve({})
+  } else {
+    resolve(toResolve)
+  }
+}
 
 module.exports = class ExtensionStore {
   async fetch() {
     return new Promise((resolve) => {
-      extension.storage.sync.get(KEYS_TO_SYNC, data => resolve(data))
+      extension.storage.sync.get(KEYS_TO_SYNC, (data) => {
+        handleDisabledSyncAndResolve(resolve, data)
+      })
     })
   }
   async sync(state) {
@@ -14,7 +27,9 @@ module.exports = class ExtensionStore {
       return result
     }, {})
     return new Promise((resolve) => {
-      extension.storage.sync.set(dataToSync, () => resolve())
+      extension.storage.sync.set(dataToSync, () => {
+        handleDisabledSyncAndResolve(resolve)
+      })
     })
   }
 }