--- a/services/common/docs/RemoteSettings.rst
+++ b/services/common/docs/RemoteSettings.rst
@@ -63,16 +63,19 @@ The ``sync`` event allows to be notified
     RemoteSettings("a-key").on("sync", event => {
       const { data: { current } } = event;
       for(const entry of current) {
         // Do something with entry...
         // await InternalAPI.reload(entry.id, entry.label, entry.weight);
       }
     });
 
+.. important::
+    If one of the event handler fails, the others handlers for the same remote settings collection won't be executed.
+
 .. note::
     Currently, the update of remote settings is triggered by the `nsBlocklistService <https://dxr.mozilla.org/mozilla-central/source/toolkit/mozapps/extensions/nsBlocklistService.js>`_ (~ every 24H).
 
 File attachments
 ----------------
 
 When an entry has a file attached to it, it has an ``attachment`` attribute, which contains the file related information (url, hash, size, mimetype, etc.). Remote files are not downloaded automatically.
 

--- a/services/common/remote-settings.js
+++ b/services/common/remote-settings.js
@@ -342,32 +342,44 @@ class RemoteSettingsClient {
           } else if (/Backoff/.test(e.message)) {
             reportStatus = UptakeTelemetry.STATUS.BACKOFF;
           } else {
             reportStatus = UptakeTelemetry.STATUS.SYNC_ERROR;
           }
           throw e;
         }
       }
-      // Read local collection of records.
-      const { data: current } = await collection.list();
 
-      // Handle the obtained records (ie. apply locally).
-      try {
-        // Execute callbacks in order and sequentially.
+      // Handle the obtained records (ie. apply locally through events).
+      // Build the event data list. It should be filtered (ie. by application target)
+      const { created: allCreated, updated: allUpdated, deleted: allDeleted } = syncResult;
+      const [created, deleted, updatedFiltered] = await Promise.all(
+          [allCreated, allDeleted, allUpdated.map(e => e.new)].map(this._filterEntries.bind(this))
+        );
+      // For updates, keep entries whose updated form is matches the target.
+      const updatedFilteredIds = new Set(updatedFiltered.map(e => e.id));
+      const updated = allUpdated.filter(({ new: { id } }) => updatedFilteredIds.has(id));
+
+      // If every changed entry is filtered, we don't even fire the event.
+      if (created.length || updated.length || deleted.length) {
+        // Read local collection of records (also filtered).
+        const { data: allData } = await collection.list();
+        const current = await this._filterEntries(allData);
+        // Fire the event: execute callbacks in order and sequentially.
         // If one fails everything fails.
-        const { created, updated, deleted } = syncResult;
         const event = { data: { current, created, updated, deleted } };
         const callbacks = this._callbacks.get("sync");
-        for (const cb of callbacks) {
-          await cb(event);
+        try {
+          for (const cb of callbacks) {
+            await cb(event);
+          }
+        } catch (e) {
+          reportStatus = UptakeTelemetry.STATUS.APPLY_ERROR;
+          throw e;
         }
-      } catch (e) {
-        reportStatus = UptakeTelemetry.STATUS.APPLY_ERROR;
-        throw e;
       }
 
       // Track last update.
       this._updateLastCheck(serverTime);
 
     } catch (e) {
       // No specific error was tracked, mark it as unknown.
       if (reportStatus === null) {

--- a/services/common/tests/unit/test_blocklist_clients.js
+++ b/services/common/tests/unit/test_blocklist_clients.js
@@ -170,16 +170,55 @@ add_task(async function test_sends_reloa
       client.maybeSync(2000, Date.now() - 1000, {loadDump: false});
     });
 
     equal(received.data.filename, client.filename);
   }
 });
 add_task(clear_state);
 
+add_task(async function test_sync_event_data_is_filtered_for_target() {
+  // Here we will synchronize 4 times, the first two to initialize the local DB and
+  // the last two about event filtered data.
+  const timestamp1 = 2000;
+  const timestamp2 = 3000;
+  const timestamp3 = 4000;
+  const timestamp4 = 5000;
+  // Fake a date value obtained from server (used to store a pref, useless here).
+  const fakeServerTime = Date.now();
+
+  for (let {client} of gBlocklistClients) {
+    // Initialize the collection with some data (local is empty, thus no ?_since)
+    await client.maybeSync(timestamp1, fakeServerTime - 30, {loadDump: false});
+    // This will pick the data with ?_since=3000.
+    await client.maybeSync(timestamp2 + 1, fakeServerTime - 20);
+
+    // In ?_since=4000 entries, no target matches. The sync event is not called.
+    let called = false;
+    client.on("sync", e => called = true);
+    await client.maybeSync(timestamp3 + 1, fakeServerTime - 10);
+    equal(called, false, `no sync event for ${client.collectionName}`);
+
+    // In ?_since=5000 entries, only one entry matches.
+    let syncEventData;
+    client.on("sync", e => syncEventData = e.data);
+    await client.maybeSync(timestamp4 + 1, fakeServerTime);
+    const { current, created, updated, deleted } = syncEventData;
+    equal(created.length + updated.length + deleted.length, 1, `event filtered data for ${client.collectionName}`);
+
+    // Since we had entries whose target does not match, the internal storage list
+    // and the event current data should differ.
+    const collection = await client.openCollection();
+    const { data: internalData } = await collection.list();
+    ok(internalData.length > current.length, `event current data for ${client.collectionName}`);
+  }
+});
+add_task(clear_state);
+
+
 // get a response for a given request from sample data
 function getSampleResponse(req, port) {
   const responses = {
     "OPTIONS": {
       "sampleHeaders": [
         "Access-Control-Allow-Headers: Content-Length,Expires,Backoff,Retry-After,Last-Modified,Total-Records,ETag,Pragma,Cache-Control,authorization,content-type,if-none-match,Alert,Next-Page",
         "Access-Control-Allow-Methods: GET,HEAD,OPTIONS,POST,DELETE,OPTIONS",
         "Access-Control-Allow-Origin: *",
@@ -317,31 +356,30 @@ function getSampleResponse(req, port) {
       "responseBody": JSON.stringify({"data": [{
         "infoURL": "https://get.adobe.com/flashplayer/",
         "blockID": "p1044",
         "matchFilename": "libflashplayer\\.so",
         "last_modified": 4000,
         "versionRange": [{
           "targetApplication": [],
           "minVersion": "11.2.202.509",
-          "maxVersion": "11.2.202.539",
+          "maxVersion": "*",
           "severity": "0",
           "vulnerabilityStatus": "1"
         }],
         "os": "Linux",
         "id": "aabad965-e556-ffe7-4191-074f5dee3df3"
       }, {
         "matchFilename": "npViewpoint.dll",
         "blockID": "p32",
         "id": "1f48af42-c508-b8ef-b8d5-609d48e4f6c9",
         "last_modified": 3500,
         "versionRange": [{
           "targetApplication": [{
             "minVersion": "3.0",
-            "guid": "{ec8030f7-c20a-464f-9b0e-13a3a9e97384}",
             "maxVersion": "*"
           }]
         }]
       }]})
     },
     "GET:/v1/buckets/blocklists/collections/gfx/records?_sort=-last_modified&_since=3000": {
       "sampleHeaders": [
         "Access-Control-Allow-Origin: *",
@@ -365,15 +403,172 @@ function getSampleResponse(req, port) {
         "blockID": "g200",
         "feature": "WEBGL_MSAA",
         "devices": [],
         "id": "c3a15ba9-e0e2-421f-e399-c995e5b8d14e",
         "last_modified": 3500,
         "os": "Darwin 11",
         "featureStatus": "BLOCKED_DEVICE"
       }]})
+    },
+    "GET:/v1/buckets/blocklists/collections/addons/records?_sort=-last_modified&_since=4000": {
+      "sampleHeaders": [
+        "Access-Control-Allow-Origin: *",
+        "Access-Control-Expose-Headers: Retry-After, Content-Length, Alert, Backoff",
+        "Content-Type: application/json; charset=UTF-8",
+        "Server: waitress",
+        "Etag: \"5000\""
+      ],
+      "status": {status: 200, statusText: "OK"},
+      "responseBody": JSON.stringify({"data": [{
+        "last_modified": 4001,
+        "versionRange": [{
+          "targetApplication": [{
+            "guid": "some-guid"
+          }],
+        }],
+        "id": "8f03b264-57b7-4263-9b15-ad91b033a034"
+      }]})
+    },
+    "GET:/v1/buckets/blocklists/collections/plugins/records?_sort=-last_modified&_since=4000": {
+      "sampleHeaders": [
+        "Access-Control-Allow-Origin: *",
+        "Access-Control-Expose-Headers: Retry-After, Content-Length, Alert, Backoff",
+        "Content-Type: application/json; charset=UTF-8",
+        "Server: waitress",
+        "Etag: \"5000\""
+      ],
+      "status": {status: 200, statusText: "OK"},
+      "responseBody": JSON.stringify({"data": [{
+        "last_modified": 4001,
+        "versionRange": [{
+          "targetApplication": [{
+            "guid": "xpcshell@tests.mozilla.org",
+            "minVersion": "0",
+            "maxVersion": "57.*"
+          }]
+        }],
+        "id": "cd3ea0b2-1ba8-4fb6-b242-976a87626116"
+      }]})
+    },
+    "GET:/v1/buckets/blocklists/collections/gfx/records?_sort=-last_modified&_since=4000": {
+      "sampleHeaders": [
+        "Access-Control-Allow-Origin: *",
+        "Access-Control-Expose-Headers: Retry-After, Content-Length, Alert, Backoff",
+        "Content-Type: application/json; charset=UTF-8",
+        "Server: waitress",
+        "Etag: \"5000\""
+      ],
+      "status": {status: 200, statusText: "OK"},
+      "responseBody": JSON.stringify({"data": [{
+        "last_modified": 4001,
+        "versionRange": [{
+          "targetApplication": [{
+            "guid": "xpcshell@tests.mozilla.org",
+            "minVersion": "99999"
+          }],
+        }],
+        "id": "86771771-e803-4006-95e9-c9275d58b3d1"
+      }]})
+    },
+    "GET:/v1/buckets/blocklists/collections/addons/records?_sort=-last_modified&_since=5000": {
+      "sampleHeaders": [
+        "Access-Control-Allow-Origin: *",
+        "Access-Control-Expose-Headers: Retry-After, Content-Length, Alert, Backoff",
+        "Content-Type: application/json; charset=UTF-8",
+        "Server: waitress",
+        "Etag: \"6000\""
+      ],
+      "status": {status: 200, statusText: "OK"},
+      "responseBody": JSON.stringify({"data": [{
+        // delete an entry with non matching target (see above)
+        "last_modified": 5001,
+        "deleted": true,
+        "id": "8f03b264-57b7-4263-9b15-ad91b033a034"
+      }, {
+        // delete entry with matching target (see above)
+        "last_modified": 5002,
+        "deleted": true,
+        "id": "9ccfac91-e463-c30c-f0bd-14143794a8dd"
+      }, {
+        // create an extra non matching
+        "last_modified": 5003,
+        "id": "75b36589-435a-48d4-8ee4-bacee3fb6119",
+        "versionRange": [{
+          "targetApplication": [{
+            "guid": "xpcshell@tests.mozilla.org",
+            "minVersion": "0",
+            "maxVersion": "57.*"
+          }]
+        }],
+      }]})
+    },
+    "GET:/v1/buckets/blocklists/collections/plugins/records?_sort=-last_modified&_since=5000": {
+      "sampleHeaders": [
+        "Access-Control-Allow-Origin: *",
+        "Access-Control-Expose-Headers: Retry-After, Content-Length, Alert, Backoff",
+        "Content-Type: application/json; charset=UTF-8",
+        "Server: waitress",
+        "Etag: \"6000\""
+      ],
+      "status": {status: 200, statusText: "OK"},
+      "responseBody": JSON.stringify({"data": [{
+        // entry with non matching target (see above)
+        "newAttribute": 42,
+        "versionRange": [{
+          "targetApplication": [{
+            "guid": "xpcshell@tests.mozilla.org",
+            "minVersion": "0",
+            "maxVersion": "57.*"
+          }]
+        }],
+        "id": "cd3ea0b2-1ba8-4fb6-b242-976a87626116"
+      }, {
+        // entry with matching target (see above)
+        "newAttribute": 42,
+        "matchFilename": "npViewpoint.dll",
+        "blockID": "p32",
+        "id": "1f48af42-c508-b8ef-b8d5-609d48e4f6c9",
+        "last_modified": 3500,
+        "versionRange": [{
+          "targetApplication": [{
+            "guid": "xpcshell@tests.mozilla.org",
+            "minVersion": "3.0",
+            "maxVersion": "*"
+          }]
+        }]
+      }]})
+    },
+    "GET:/v1/buckets/blocklists/collections/gfx/records?_sort=-last_modified&_since=5000": {
+      "sampleHeaders": [
+        "Access-Control-Allow-Origin: *",
+        "Access-Control-Expose-Headers: Retry-After, Content-Length, Alert, Backoff",
+        "Content-Type: application/json; charset=UTF-8",
+        "Server: waitress",
+        "Etag: \"6000\""
+      ],
+      "status": {status: 200, statusText: "OK"},
+      "responseBody": JSON.stringify({"data": [{
+        "versionRange": [{
+          "targetApplication": [{
+            "guid": "xpcshell@tests.mozilla.org",
+            "minVersion": "0",
+            "maxVersion": "*"
+          }]
+        }],
+        "id": "43031a81-5f36-4eef-9b35-52f0bbeba363"
+      }, {
+        "versionRange": [{
+          "targetApplication": [{
+            "guid": "xpcshell@tests.mozilla.org",
+            "minVersion": "0",
+            "maxVersion": "3"
+          }]
+        }],
+        "id": "75a06bd3-f906-427d-a448-02092ee589fc"
+      }]})
     }
   };
   return responses[`${req.method}:${req.path}?${req.queryString}`] ||
          responses[`${req.method}:${req.path}`] ||
          responses[req.method];
 
 }

--- a/services/common/tests/unit/test_blocklist_signatures.js
+++ b/services/common/tests/unit/test_blocklist_signatures.js
@@ -444,29 +444,26 @@ add_task(async function test_check_signa
     "GET:/v1/buckets/blocklists/collections/certificates/records?_sort=id":
       [RESPONSE_COMPLETE_INITIAL_SORTED_BY_ID]
   };
 
   registerHandlers(badSigGoodSigResponses);
 
   startHistogram = getUptakeTelemetrySnapshot(TELEMETRY_HISTOGRAM_KEY);
 
-  let retrySyncData;
-  OneCRLBlocklistClient.on("sync", ({ data }) => { retrySyncData = data; });
+  let syncEventSent = false;
+  OneCRLBlocklistClient.on("sync", ({ data }) => { syncEventSent = true; });
 
   await OneCRLBlocklistClient.maybeSync(5000, startTime);
 
   endHistogram = getUptakeTelemetrySnapshot(TELEMETRY_HISTOGRAM_KEY);
 
-  // since we only fixed the signature, and no data was changed, the sync result
-  // will be called with empty lists of created/updated/deleted.
-  equal(retrySyncData.current.length, 2);
-  equal(retrySyncData.created.length, 0);
-  equal(retrySyncData.updated.length, 0);
-  equal(retrySyncData.deleted.length, 0);
+  // since we only fixed the signature, and no data was changed, the sync event
+  // was not sent.
+  equal(syncEventSent, false);
 
   // ensure that the failure count is incremented for a succesful sync with an
   // (initial) bad signature - only SERVICES_SETTINGS_SYNC_SIG_FAIL should
   // increment.
   expectedIncrements = {[UptakeTelemetry.STATUS.SIGNATURE_ERROR]: 1};
   checkUptakeTelemetry(startHistogram, endHistogram, expectedIncrements);
 
 
@@ -488,27 +485,24 @@ add_task(async function test_check_signa
       [RESPONSE_EMPTY_INITIAL],
   };
 
   // ensure our collection hasn't been replaced with an older, empty one
   await checkRecordCount(OneCRLBlocklistClient, 2);
 
   registerHandlers(badSigGoodOldResponses);
 
-  let oldChangesData;
-  OneCRLBlocklistClient.on("sync", ({ data }) => { oldChangesData = data; });
+  syncEventSent = false;
+  OneCRLBlocklistClient.on("sync", ({ data }) => { syncEventSent = true; });
 
   await OneCRLBlocklistClient.maybeSync(5000, startTime);
 
-  // Local data was unchanged, since it was never than the one returned by the server.
-  equal(oldChangesData.current.length, 2);
-  equal(oldChangesData.created.length, 0);
-  equal(oldChangesData.updated.length, 0);
-  equal(oldChangesData.deleted.length, 0);
-
+  // Local data was unchanged, since it was never than the one returned by the server,
+  // thus the sync event is not sent.
+  equal(syncEventSent, false);
 
   const badLocalContentGoodSigResponses = {
     // In this test, we deliberately serve a bad signature initially. The
     // subsequent signature returned is a valid one for the three item
     // collection.
     "GET:/v1/buckets/blocklists/collections/certificates?":
       [RESPONSE_META_BAD_SIG, RESPONSE_META_THREE_ITEMS_SIG],
     // The next request is for the full collection. This will be checked