diff --git a/include/v8-version-string.h b/include/v8-version-string.h
index 8faed2a740..f06d54aa7d 100644
--- a/include/v8-version-string.h
+++ b/include/v8-version-string.h
@@ -18,8 +18,12 @@
 
 #ifndef V8_EMBEDDER_STRING
 #define V8_EMBEDDER_STRING ""
+#define V8_EMBEDDER_STRING2 ""
+#else
+#define V8_EMBEDDER_STRING2 " " V8_EMBEDDER_STRING
 #endif
 
+
 #define V8_SX(x) #x
 #define V8_S(x) V8_SX(x)
 
@@ -27,12 +31,12 @@
 #define V8_VERSION_STRING                                        \
   V8_S(V8_MAJOR_VERSION)                                         \
   "." V8_S(V8_MINOR_VERSION) "." V8_S(V8_BUILD_NUMBER) "." V8_S( \
-      V8_PATCH_LEVEL) V8_EMBEDDER_STRING V8_CANDIDATE_STRING
+      V8_PATCH_LEVEL) V8_EMBEDDER_STRING2 V8_CANDIDATE_STRING
 #else
 #define V8_VERSION_STRING                              \
   V8_S(V8_MAJOR_VERSION)                               \
   "." V8_S(V8_MINOR_VERSION) "." V8_S(V8_BUILD_NUMBER) \
-      V8_EMBEDDER_STRING V8_CANDIDATE_STRING
+      V8_EMBEDDER_STRING2 V8_CANDIDATE_STRING
 #endif
 
 #endif  // V8_VERSION_STRING_H_
diff --git a/src/flags/flag-definitions.h b/src/flags/flag-definitions.h
index a5ea688504..5681b82ed6 100644
--- a/src/flags/flag-definitions.h
+++ b/src/flags/flag-definitions.h
@@ -725,15 +725,15 @@ DEFINE_BOOL(trace_baseline_concurrent_compilation, false,
 #define FLAG FLAG_FULL
 
 // Internalize into a shared string table in the shared isolate
-DEFINE_BOOL(shared_string_table, false, "internalize strings into shared table")
+DEFINE_BOOL(shared_string_table, true, "internalize strings into shared table")
 DEFINE_IMPLICATION(harmony_struct, shared_string_table)
-DEFINE_BOOL(shared_string_table_using_shared_space, false,
+DEFINE_BOOL(shared_string_table_using_shared_space, true,
             "internalize strings into shared table")
 DEFINE_IMPLICATION(shared_string_table_using_shared_space, shared_string_table)
 DEFINE_IMPLICATION(shared_string_table_using_shared_space, shared_space)
 DEFINE_IMPLICATION(harmony_struct, shared_string_table)
 DEFINE_BOOL(
-    always_use_string_forwarding_table, false,
+    always_use_string_forwarding_table, true,
     "use string forwarding table instead of thin strings for all strings")
 // With --always-use-string-forwarding-table, we can have young generation
 // string entries in the forwarding table, requiring table updates when these
@@ -1269,7 +1269,7 @@ DEFINE_BOOL(separate_gc_phases, false,
 DEFINE_BOOL(global_gc_scheduling, true,
             "enable GC scheduling based on global memory")
 DEFINE_BOOL(gc_global, false, "always perform global GCs")
-DEFINE_BOOL(shared_space, false,
+DEFINE_BOOL(shared_space, true,
             "Implement shared heap as shared space on a main isolate.")
 
 // TODO(12950): The next two flags only have an effect if
diff --git a/src/heap/concurrent-allocator.cc b/src/heap/concurrent-allocator.cc
index 7f63bc09bd..359d9abe3d 100644
--- a/src/heap/concurrent-allocator.cc
+++ b/src/heap/concurrent-allocator.cc
@@ -100,7 +100,10 @@ void ConcurrentAllocator::FreeLinearAllocationArea() {
         ->DestroyBlackAreaBackground(lab_.top(), lab_.limit());
   }
 
-  MakeLabIterable();
+  if (!(context_ == Context::kNotGC && !owning_heap()->incremental_marking())) {
+    MakeLabIterable();
+  }
+
   ResetLab();
 }
 
@@ -283,6 +286,7 @@ AllocationResult ConcurrentAllocator::AllocateOutsideLab(
 
 bool ConcurrentAllocator::IsBlackAllocationEnabled() const {
   return context_ == Context::kNotGC &&
+         owning_heap()->incremental_marking() &&
          owning_heap()->incremental_marking()->black_allocation();
 }
 
diff --git a/src/heap/safepoint.cc b/src/heap/safepoint.cc
index 87a40837d0..9dfd95a5e5 100644
--- a/src/heap/safepoint.cc
+++ b/src/heap/safepoint.cc
@@ -315,9 +315,31 @@ void GlobalSafepoint::RemoveClient(Isolate* client) {
 
   // A shared heap may have already acquired the client mutex to perform a
   // shared GC. We need to park the Isolate here to allow for a shared GC.
+
+  if (!client) {
+    client->shared_isolate_ = nullptr;
+    return;
+  }
+
+  if (!client->heap()) {
+    client->shared_isolate_ = nullptr;
+    return;
+  }
+
   IgnoreLocalGCRequests ignore_gc_requests(client->heap());
-  ParkedRecursiveMutexGuard guard(client->main_thread_local_heap(),
-                                  &clients_mutex_);
+
+  if (!client->main_thread_local_heap()) {
+    client->shared_isolate_ = nullptr;
+    return;
+  }
+
+  if (!client->main_thread_local_heap()->heap()) {
+    client->shared_isolate_ = nullptr;
+    return;
+  }
+
+  //ParkedRecursiveMutexGuard guard(client->main_thread_local_heap(),
+  //                                &clients_mutex_);
 
   if (client->global_safepoint_next_client_isolate_) {
     client->global_safepoint_next_client_isolate_
diff --git a/src/snapshot/snapshot.cc b/src/snapshot/snapshot.cc
index 3af67804cf..0bccd7af37 100644
--- a/src/snapshot/snapshot.cc
+++ b/src/snapshot/snapshot.cc
@@ -703,21 +703,21 @@ base::Vector<const byte> SnapshotImpl::ExtractContextData(
 }
 
 void SnapshotImpl::CheckVersion(const v8::StartupData* data) {
-  if (!Snapshot::VersionIsValid(data)) {
-    char version[kVersionStringLength];
-    memset(version, 0, kVersionStringLength);
-    CHECK_LT(kVersionStringOffset + kVersionStringLength,
-             static_cast<uint32_t>(data->raw_size));
-    Version::GetString(base::Vector<char>(version, kVersionStringLength));
-    FATAL(
-        "Version mismatch between V8 binary and snapshot.\n"
-        "#   V8 binary version: %.*s\n"
-        "#    Snapshot version: %.*s\n"
-        "# The snapshot consists of %d bytes and contains %d context(s).",
-        kVersionStringLength, version, kVersionStringLength,
-        data->data + kVersionStringOffset, data->raw_size,
-        ExtractNumContexts(data));
-  }
+  //if (!Snapshot::VersionIsValid(data)) {
+  //  char version[kVersionStringLength];
+  //  memset(version, 0, kVersionStringLength);
+  //  CHECK_LT(kVersionStringOffset + kVersionStringLength,
+  //           static_cast<uint32_t>(data->raw_size));
+  //  Version::GetString(base::Vector<char>(version, kVersionStringLength));
+  //  FATAL(
+  //      "Version mismatch between V8 binary and snapshot.\n"
+  //      "#   V8 binary version: %.*s\n"
+  //      "#    Snapshot version: %.*s\n"
+  //      "# The snapshot consists of %d bytes and contains %d context(s).",
+  //      kVersionStringLength, version, kVersionStringLength,
+  //      data->data + kVersionStringOffset, data->raw_size,
+  //      ExtractNumContexts(data));
+  //}
 }
 
 namespace {