diff --git a/packaging/android/Android.mk b/packaging/android/Android.mk
index ddcb9b8a..b03a1fde 100644
--- a/packaging/android/Android.mk
+++ b/packaging/android/Android.mk
@@ -12,7 +12,6 @@ LOCAL_CFLAGS += -DHAVE_USLEEP=1
 LOCAL_CFLAGS += -DSQLITE_ENABLE_FTS5 
 LOCAL_CFLAGS += -DSQLITE_ENABLE_RTREE
 LOCAL_CFLAGS += -DSQLITE_ENABLE_FTS3
-LOCAL_CFLAGS += -DSQLITE_ENABLE_BATCH_ATOMIC_WRITE
 
 # Select default encryption scheme
 # ChaCha20-Poly1305 is the default
diff --git a/src/cipher_common.c b/src/cipher_common.c
index 38e0fba8..40f42b5b 100644
--- a/src/cipher_common.c
+++ b/src/cipher_common.c
@@ -688,7 +688,11 @@ SQLITE_PRIVATE unsigned char* mcReadDatabaseHeader(Codec* codec, unsigned char*
       sqlite3_int64 fileSize = 0;
       int ret = sqlite3OsFileSize(fd, &fileSize);
       if (fileSize == 0)
+      {
+        /* Empty file: there is no salt yet, a random salt will be generated */
         *rc = SQLITE_OK;
+        return NULL;
+      }
     }
     if (*rc == SQLITE_OK)
       hdr = dbHeader;
diff --git a/src/memory_secure.c b/src/memory_secure.c
index 937149d6..adb99c49 100644
--- a/src/memory_secure.c
+++ b/src/memory_secure.c
@@ -209,16 +209,26 @@ SQLITE_PRIVATE void sqlite3mcInitMemoryMethods()
 #if SQLITE3MC_SECURE_MEMORY
   if (!mcSecureMemoryInitialized)
   {
-    if (sqlite3_config(SQLITE_CONFIG_GETMALLOC, &mcDefaultMemoryMethods) == SQLITE_OK)
+    sqlite3_mem_methods currentMemoryMethods;
+    if (sqlite3_config(SQLITE_CONFIG_GETMALLOC, &currentMemoryMethods) == SQLITE_OK)
     {
-      mcSecureMemoryMethods.pAppData = mcDefaultMemoryMethods.pAppData;
-      if (sqlite3_config(SQLITE_CONFIG_MALLOC, &mcSecureMemoryMethods) == SQLITE_OK)
+      if (currentMemoryMethods.xMalloc == mcSecureMemoryMethods.xMalloc)
       {
+        /* Still installed after sqlite3_shutdown(), do not wrap it a second time */
         mcSecureMemoryInitialized = 1;
       }
       else
       {
-        mcSecureMemoryFlag = mcSecureMemoryInitialized = 0;
+        mcDefaultMemoryMethods = currentMemoryMethods;
+        mcSecureMemoryMethods.pAppData = mcDefaultMemoryMethods.pAppData;
+        if (sqlite3_config(SQLITE_CONFIG_MALLOC, &mcSecureMemoryMethods) == SQLITE_OK)
+        {
+          mcSecureMemoryInitialized = 1;
+        }
+        else
+        {
+          mcSecureMemoryFlag = mcSecureMemoryInitialized = 0;
+        }
       }
     }
     else
diff --git a/src/sqlite3mc_vfs.c b/src/sqlite3mc_vfs.c
index a7182096..3e8f4da7 100644
--- a/src/sqlite3mc_vfs.c
+++ b/src/sqlite3mc_vfs.c
@@ -723,8 +723,8 @@ static sqlite3mc_file* mcFindDbMainFileName(sqlite3mc_vfs* mcVfs, const char* zF
 static sqlite3mc_vfs* mcFindVfs(sqlite3* db, const char* zDbName)
 {
   int dbIndex = (zDbName) ? sqlite3FindDbName(db, zDbName) : 0;
-  Pager* pager = sqlite3BtreePager(db->aDb[dbIndex].pBt);
-  sqlite3_vfs* dbVfs = pager->pVfs;
+  Btree* pBt = (dbIndex >= 0) ? db->aDb[dbIndex].pBt : NULL;
+  sqlite3_vfs* dbVfs = (pBt != NULL) ? sqlite3BtreePager(pBt)->pVfs : NULL;
 
   sqlite3mc_vfs* pVfsMC = NULL;
   if (dbVfs && dbVfs->xOpen == mcVfsOpen)
diff --git a/test/rekeytest.c b/test/rekeytest.c
index 4eb8adef..62a241e3 100644
--- a/test/rekeytest.c
+++ b/test/rekeytest.c
@@ -21,7 +21,8 @@
 **          always be supplied (rekey, failure case, plain -> encrypted)
 ** Part 8 : salt management (random salt, salt in memory across several rekeys,
 **          rekey_salt=on/off) and behaviour when reading the file header
-**          (unencrypted/empty/too short file, I/O error while reading the header)
+**          (unencrypted/empty/too short file, I/O error while reading the header),
+**          key, rekey and backup for a schema name without a database file
 **
 ** Invariant in parts 3 and 6 (after every rekey, whether it failed or not):
 **   exactly ONE of the two states (old/new) is completely readable
@@ -1765,6 +1766,25 @@ static void t8_short_header(void)
     rc = open_state("chacha20", "k", &db, &n);
     CHECK(rc == SQLITE_OK && n == 1, "reopened and readable without cipher_salt");
     if (db) sqlite3_close(db);
+
+    /* A second new DB with the same key must get a different salt */
+    {
+      unsigned char h2[16];
+      remove_files();
+      write_bytes(DBFILE, 0);
+      rc = sqlite3_open_v2(DBFILE, &db, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, "multipleciphers-faulty");
+      if (rc == SQLITE_OK)
+      {
+        set_params(db, "chacha20");
+        keyRc = sqlite3_key(db, "k", 1);
+        rc = sqlite3_exec(db, "CREATE TABLE t(a INTEGER PRIMARY KEY, b TEXT)", 0, 0, 0);
+        if (keyRc != SQLITE_OK) rc = keyRc;
+      }
+      sqlite3_close(db);
+      db = 0;
+      CHECK(rc == SQLITE_OK && read_header_salt(h2) && memcmp(h, h2, 16) != 0,
+            "second empty file + same key: different salt");
+    }
   }
 
   for (i = 0; i < sizeof(sizes) / sizeof(sizes[0]); i++)
@@ -1827,6 +1847,33 @@ static void t8_header_read_error(void)
   CHECK(state_ok("chacha20", "old-key", g_nrows), "afterwards completely readable with the correct key");
 }
 
+/* Key, rekey and backup for a schema name without a database file
+** (unknown name, "temp" before it is used): an error, no crash */
+static void t8_schema_without_file(void)
+{
+  sqlite3* db = 0;
+  sqlite3* dbDest = 0;
+  sqlite3_backup* backup;
+  int rc;
+
+  printf("\n== key, rekey and backup for a schema without database file ==\n");
+  snprintf(g_ctx, sizeof(g_ctx), "Part 8: schema_without_file");
+  remove_files();
+  rc = sqlite3_open_v2(DBFILE, &db, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, "multipleciphers-faulty");
+  CHECK(rc == SQLITE_OK, "DB opened");
+  if (rc != SQLITE_OK) return;
+  CHECK(sqlite3_key_v2(db, "nosuchdb", "k", 1) != SQLITE_OK, "key for an unknown schema fails");
+  CHECK(sqlite3_key_v2(db, "temp", "k", 1) != SQLITE_OK, "key for temp fails");
+  CHECK(sqlite3_rekey_v2(db, "nosuchdb", "k", 1) != SQLITE_OK, "rekey for an unknown schema fails");
+  CHECK(sqlite3_rekey_v2(db, "temp", "k", 1) != SQLITE_OK, "rekey for temp fails");
+  rc = sqlite3_open(":memory:", &dbDest);
+  backup = (rc == SQLITE_OK) ? sqlite3_backup_init(dbDest, "main", db, "temp") : NULL;
+  if (backup) sqlite3_backup_finish(backup);
+  CHECK(rc == SQLITE_OK, "backup from temp returns without a crash");
+  sqlite3_close(dbDest);
+  sqlite3_close(db);
+}
+
 static void run_part8(void)
 {
   t8_random_salt();
@@ -1837,6 +1884,7 @@ static void run_part8(void)
   t8_plain_with_key();
   t8_short_header();
   t8_header_read_error();
+  t8_schema_without_file();
 }
 
 /* ------------------------------------------------------------------ */