diff --git a/browser/base/content/sanitize.js b/browser/base/content/sanitize.js
index 153bfd651fea..ba10cafa492c 100644
--- a/browser/base/content/sanitize.js
+++ b/browser/base/content/sanitize.js
@@ -65,7 +65,13 @@ Sanitizer.prototype = {
       var itemsToClear = [...aItemsToClear];
     } else {
       let branch = Services.prefs.getBranch(this.prefDomain);
-      itemsToClear = Object.keys(this.items).filter(itemName => branch.getBoolPref(itemName));
+      itemsToClear = Object.keys(this.items).filter(itemName => {
+        try {
+          return branch.getBoolPref(itemName);
+        } catch (ex) {
+          return false;
+        }
+      });
     }
 
     // Ensure open windows get cleared first, if they're in our list, so that they don't stick
diff --git a/browser/components/places/tests/unit/test_clearHistory_shutdown.js b/browser/components/places/tests/unit/test_clearHistory_shutdown.js
index a516e51bc24b..c87bffc4d73d 100644
--- a/browser/components/places/tests/unit/test_clearHistory_shutdown.js
+++ b/browser/components/places/tests/unit/test_clearHistory_shutdown.js
@@ -71,13 +71,11 @@ add_task(function* test_execute() {
   }
   do_print("Add cache.");
   yield storeCache(FTP_URL, "testData");
-});
 
-add_task(function* run_test_continue() {
   do_print("Simulate and wait shutdown.");
   yield shutdownPlaces();
 
-  let stmt = DBConn().createStatement(
+  let stmt = DBConn(true).createStatement(
     "SELECT id FROM moz_places WHERE url = :page_url "
   );
 
@@ -93,13 +91,7 @@ add_task(function* run_test_continue() {
 
   do_print("Check cache");
   // Check cache.
-  let promiseCacheChecked = checkCache(FTP_URL);
-
-  do_print("Shutdown the download manager");
-  // Shutdown the download manager.
-  Services.obs.notifyObservers(null, "quit-application", null);
-
-  yield promiseCacheChecked;
+  yield checkCache(FTP_URL);
 });
 
 function storeCache(aURL, aContent) {
diff --git a/toolkit/components/places/PlacesUtils.jsm b/toolkit/components/places/PlacesUtils.jsm
index e5a750c77225..c36121640d64 100644
--- a/toolkit/components/places/PlacesUtils.jsm
+++ b/toolkit/components/places/PlacesUtils.jsm
@@ -2075,6 +2075,19 @@ XPCOMUtils.defineLazyGetter(this, "bundle", function() {
          createBundle(PLACES_STRING_BUNDLE_URI);
 });
 
+// A promise resolved once the Sqlite.jsm connections
+// can be closed.
+let promiseCanCloseConnection = function() {
+  let TOPIC = "places-will-close-connection";
+  return new Promise(resolve => {
+    let observer = function() {
+      Services.obs.removeObserver(observer, TOPIC);
+      resolve();
+    }
+    Services.obs.addObserver(observer, TOPIC, false)
+  });
+};
+
 XPCOMUtils.defineLazyGetter(this, "gAsyncDBConnPromised",
   () => new Promise((resolve) => {
     Sqlite.cloneStorageConnection({
@@ -2082,12 +2095,23 @@ XPCOMUtils.defineLazyGetter(this, "gAsyncDBConnPromised",
       readOnly:   true
     }).then(conn => {
       try {
-        Sqlite.shutdown.addBlocker(
-          "PlacesUtils read-only connection closing",
-          conn.close.bind(conn));
-        PlacesUtils.history.shutdownClient.jsclient.addBlocker(
-          "PlacesUtils read-only connection closing",
-          conn.close.bind(conn));
+        let state = "0. not started";
+
+        let promiseReady = promiseCanCloseConnection();
+        let promiseShutdownComplete = Task.async(function*() {
+          // Don't close the connection as long as it might be used.
+          state = "1. waiting for `places-will-close-connection`";
+          yield promiseReady;
+
+          // But close the connection before Sqlite shutdown.
+          state = "2. closing the connection";
+          yield conn.close();
+
+          state = "3. done";
+        })();
+        Sqlite.shutdown.addBlocker("PlacesUtils read-only connection closing",
+          promiseShutdownComplete,
+          () => state);
       } catch(ex) {
         // It's too late to block shutdown, just close the connection.
         conn.close();
@@ -2104,12 +2128,23 @@ XPCOMUtils.defineLazyGetter(this, "gAsyncDBWrapperPromised",
       connection: PlacesUtils.history.DBConnection,
     }).then(conn => {
       try {
-        Sqlite.shutdown.addBlocker(
-          "PlacesUtils wrapped connection closing",
-          conn.close.bind(conn));
-        PlacesUtils.history.shutdownClient.jsclient.addBlocker(
-          "PlacesUtils wrapped connection closing",
-          conn.close.bind(conn));
+        let state = "0. not started";
+
+        let promiseReady = promiseCanCloseConnection();
+        let promiseShutdownComplete = Task.async(function*() {
+          // Don't close the connection as long as it might be used.
+          state = "1. waiting for `places-will-close-connection`";
+          yield promiseReady;
+
+          // But close the connection before Sqlite shutdown.
+          state = "2. closing the connection";
+          yield conn.close();
+
+          state = "3. done";
+        })();
+        Sqlite.shutdown.addBlocker("PlacesUtils wrapped connection closing",
+          promiseShutdownComplete,
+          () => state);
       } catch(ex) {
         // It's too late to block shutdown, just close the connection.
         conn.close();