diff --git a/chrome/content/zotero/preferences/preferences_sync.js b/chrome/content/zotero/preferences/preferences_sync.js
index 15f1679a9..8b4263e73 100644
--- a/chrome/content/zotero/preferences/preferences_sync.js
+++ b/chrome/content/zotero/preferences/preferences_sync.js
@@ -72,7 +72,7 @@ Zotero_Preferences.Sync = {
 		}
 		
 		if (oldProtocol == 'zotero' && protocol == 'webdav') {
-			var sql = "SELECT COUNT(*) FROM version WHERE schema='storage_zfs'";
+			var sql = "SELECT COUNT(*) FROM version WHERE schema LIKE 'storage_zfs%'";
 			if (Zotero.DB.valueQuery(sql)) {
 				var ps = Components.classes["@mozilla.org/embedcomp/prompt-service;1"]
 										.getService(Components.interfaces.nsIPromptService);
diff --git a/chrome/content/zotero/xpcom/storage/zfs.js b/chrome/content/zotero/xpcom/storage/zfs.js
index cdad1f030..7ec6513a9 100644
--- a/chrome/content/zotero/xpcom/storage/zfs.js
+++ b/chrome/content/zotero/xpcom/storage/zfs.js
@@ -1043,6 +1043,10 @@ Zotero.Sync.Storage.ZFS = (function () {
 	 */
 	obj._purgeDeletedStorageFiles = function () {
 		return Q.fcall(function () {
+			// Cache the credentials at the root
+			return self._cacheCredentials();
+		}.bind(this))
+		then(function () {
 			// If we don't have a user id we've never synced and don't need to bother
 			if (!Zotero.userID) {
 				return false;