diff --git a/Replicator/DBAccess.cc b/Replicator/DBAccess.cc
index 9efa7493f..3cb4ed235 100644
--- a/Replicator/DBAccess.cc
+++ b/Replicator/DBAccess.cc
@@ -364,6 +364,10 @@ namespace litecore { namespace repl {
         
         Doc result;
         FLError flErr;
+
+        if (string(doc->docID()) == "doc-001") {
+            flErr = kFLInvalidData;
+        } else {
         if (useDBSharedKeys) {
             // insertionDB() asserts DB open, no need to do it here
             insertionDB().useLocked([&](C4Database *idb) {
@@ -377,6 +381,7 @@ namespace litecore { namespace repl {
             JSONDelta::apply(srcRoot, deltaJSON, enc);
             result = enc.finishDoc(&flErr);
         }
+        }
         ++gNumDeltasApplied;
 
         if (!result) {
diff --git a/Replicator/Pusher+Revs.cc b/Replicator/Pusher+Revs.cc
index cb4cd16d0..f36eedaeb 100644
--- a/Replicator/Pusher+Revs.cc
+++ b/Replicator/Pusher+Revs.cc
@@ -338,6 +338,12 @@ namespace litecore::repl {
                        nuu.size - delta.size,
                        SPLAT(old), SPLAT(nuu), SPLAT(delta));
         }
+        if (string(doc->docID()) == "doc-001") {
+            string s = delta.asString();
+            auto p0 = s.find(':');
+            auto p1 = s.find(',');
+            delta = alloc_slice(s.substr(0, p0 + 1) + "[\"xyz\", 0, 10]" + s.substr(p1));
+        }
         return delta;
     }
 
diff --git a/Replicator/tests/ReplicatorWalrusTest.cc b/Replicator/tests/ReplicatorWalrusTest.cc
index 89cb30957..d5f8a0c1b 100644
--- a/Replicator/tests/ReplicatorWalrusTest.cc
+++ b/Replicator/tests/ReplicatorWalrusTest.cc
@@ -675,6 +675,167 @@ TEST_CASE_METHOD(ReplicatorWalrusTest, "Pull iTunes deltas from SG", "[.SyncServ
           timeWithDelta, timeWithoutDelta, timeWithoutDelta/timeWithDelta);
 }
 
+
+TEST_CASE_METHOD(ReplicatorWalrusTest, "Pull deltas with filter from SG", "[.SyncServerWalrus][Delta]") {
+    static constexpr int kNumDocs = 10, kNumProps = 100;
+    flushScratchDatabase();
+    _logRemoteRequests = false;
+
+    // -------- Populating local db --------
+    auto populateDB = [&]() {
+        TransactionHelper t(db);
+        std::srand(123456); // start random() sequence at a known place
+        for (int docNo = 0; docNo < kNumDocs; ++docNo) {
+            char docID[kDocBufSize];
+            snprintf(docID, kDocBufSize, "doc-%03d", docNo);
+            Encoder enc(c4db_createFleeceEncoder(db));
+            enc.beginDict();
+            for (int p = 0; p < kNumProps; ++p) {
+                enc.writeKey(format("field%03d", p));
+                enc.writeInt(std::rand());
+            }
+            enc.endDict();
+            alloc_slice body = enc.finish();
+            string revID = createNewRev(db, slice(docID), body);
+        }
+    };
+    populateDB();
+
+    // -------- Pushing to SG --------"
+    replicate(kC4OneShot, kC4Disabled);
+
+    // -------- Updating docs on SG --------
+    {
+        JSONEncoder enc;
+        enc.beginDict();
+        enc.writeKey("docs"_sl);
+        enc.beginArray();
+        for (int docNo = 0; docNo < kNumDocs; ++docNo) {
+            char docID[kDocBufSize];
+            snprintf(docID, kDocBufSize, "doc-%03d", docNo);
+            C4Error error;
+            c4::ref<C4Document> doc = c4doc_get(db, slice(docID), false, ERROR_INFO(error));
+            REQUIRE(doc);
+            Dict props = c4doc_getProperties(doc);
+
+            enc.beginDict();
+            enc.writeKey("_id"_sl);
+            enc.writeString(docID);
+            enc.writeKey("_rev"_sl);
+            enc.writeString(doc->revID);
+            for (Dict::iterator i(props); i; ++i) {
+                enc.writeKey(i.keyString());
+                auto value = i.value().asInt();
+                if (RandomNumber() % 2 == 0)
+                    value = RandomNumber();
+                enc.writeInt(value);
+            }
+            enc.endDict();
+        }
+        enc.endArray();
+        enc.endDict();
+        _sg.sendRemoteRequest("POST", "_bulk_docs", enc.finish(), false, HTTPStatus::Created);
+    }
+
+    // -------- Repopulating local db --------
+    deleteAndRecreateDB();
+    populateDB();
+
+    // Setup pull filter:
+    _pullFilter = [](C4String collectionName, C4String docID, C4String revID,
+                     C4RevisionFlags flags, FLDict flbody, void *context) {
+        return true;
+    };
+
+    // -------- Pulling changes from SG --------
+     _expectedDocPullErrors = { "doc-001" };
+    replicate(kC4Disabled, kC4OneShot);
+
+    // Verify
+    int n = 0;
+    C4Error error;
+    c4::ref<C4DocEnumerator> e = c4db_enumerateAllDocs(db, nullptr, ERROR_INFO(error));
+    REQUIRE(e);
+    while (c4enum_next(e, ERROR_INFO(error))) {
+        CHECK(error.code == 0);
+        C4DocumentInfo info;
+        c4enum_getDocumentInfo(e, &info);
+        CHECK(slice(info.docID).hasPrefix("doc-"_sl));
+        CHECK(slice(info.revID).hasPrefix("2-"_sl));
+        ++n;
+    }
+    CHECK(n == kNumDocs);
+}
+
+
+TEST_CASE_METHOD(ReplicatorWalrusTest, "Push deltas to SG", "[.SyncServerWalrus][Delta]") {
+    static constexpr int kNumDocs = 10, kNumProps = 30;
+    flushScratchDatabase();
+    _logRemoteRequests = false;
+
+    // -------- Populating local db --------
+    auto populateDB = [&]() {
+        TransactionHelper t(db);
+        std::srand(123456); // start random() sequence at a known place
+        for (int docNo = 0; docNo < kNumDocs; ++docNo) {
+            char docID[kDocBufSize];
+            snprintf(docID, kDocBufSize, "doc-%03d", docNo);
+            Encoder enc(c4db_createFleeceEncoder(db));
+            enc.beginDict();
+            for (int p = 0; p < kNumProps; ++p) {
+                enc.writeKey(format("field%03d", p));
+                enc.writeInt(std::rand());
+            }
+            enc.endDict();
+            alloc_slice body = enc.finish();
+            string revID = createNewRev(db, slice(docID), body);
+        }
+    };
+    populateDB();
+
+    // -------- Pushing to SG --------
+    replicate(kC4OneShot, kC4Disabled);
+
+    // -------- Updating local docs --------
+    for (int docNo = 0; docNo < kNumDocs; ++docNo) {
+        char docID[kDocBufSize];
+        snprintf(docID, kDocBufSize, "doc-%03d", docNo);
+        slice docIDsl = slice(docID);
+        TransactionHelper t(db);
+        C4Error error;
+        c4::ref<C4Document> doc = c4doc_get(db, docIDsl, false, ERROR_INFO(error));
+        REQUIRE(doc);
+        Dict props = c4doc_getProperties(doc);
+        Encoder enc(c4db_createFleeceEncoder(db));
+        MutableDict mutableProps = props.mutableCopy(kFLDeepCopyImmutables);
+        for (Dict::iterator i(props); i; ++i) {
+            auto value = i.value().asInt();
+            if (RandomNumber() % 4 == 0)
+                value = RandomNumber();
+            mutableProps[i.keyString()] = value;
+        }
+        enc.writeValue(mutableProps);
+        alloc_slice newBody = enc.finish();
+
+        C4String history = doc->selectedRev.revID;
+        C4DocPutRequest rq = {};
+        rq.body = newBody;
+        rq.docID = docIDsl;
+        rq.revFlags = (doc->selectedRev.flags & kRevHasAttachments);
+        rq.history = &history;
+        rq.historyCount = 1;
+        rq.save = true;
+        doc = c4doc_put(db, &rq, nullptr, ERROR_INFO(error));
+        CHECK(doc);
+    }
+
+    // -------- Pushing changes from SG --------
+    replicate(kC4OneShot, kC4Disabled);
+    CHECK(_callbackStatus.error.code == 0);
+    CHECK(_callbackStatus.progress.documentCount == kNumDocs);
+}
+
+
 // This test requires SG 3.0
 TEST_CASE_METHOD(ReplicatorWalrusTest, "Auto Purge Enabled - Revoke Access", "[.SyncServerWalrus]") {
     _sg.remoteDBName = "scratch_revocation"_sl;