diff --git a/electrum/json_db.py b/electrum/json_db.py
index b4b56a38d..cb1d8adb7 100644
--- a/electrum/json_db.py
+++ b/electrum/json_db.py
@@ -27,6 +27,7 @@ import copy
 import json
 
 from . import util
+from .util import WalletFileException
 from .logging import Logger
 
 JsonDBJsonEncoder = util.MyEncoder
@@ -166,8 +167,20 @@ class JsonDB(Logger):
     def __init__(self, data):
         Logger.__init__(self)
         self.lock = threading.RLock()
-        self.data = data
         self._modified = False
+        # load data
+        if data:
+            self.load_data(data)
+        else:
+            self.data = {}
+
+    def load_data(self, s):
+        try:
+            self.data = json.loads(s)
+        except Exception:
+            raise WalletFileException("Cannot read wallet file. (parsing failed)")
+        if not isinstance(self.data, dict):
+            raise WalletFileException("Malformed wallet file (not dict)")
 
     def set_modified(self, b):
         with self.lock:
@@ -250,3 +263,18 @@ class JsonDB(Logger):
             else:
                 v = constructor(v)
         return v
+
+    def write(self, storage: 'WalletStorage'):
+        with self.lock:
+            self._write(storage)
+
+    def _write(self, storage: 'WalletStorage'):
+        if threading.current_thread().daemon:
+            self.logger.warning('daemon thread cannot write db')
+            return
+        if not self.modified():
+            return
+        json_str = self.dump(human_readable=not storage.is_encrypted())
+        storage.write(json_str)
+        self.set_modified(False)
+
diff --git a/electrum/wallet_db.py b/electrum/wallet_db.py
index cf889d453..255faed4a 100644
--- a/electrum/wallet_db.py
+++ b/electrum/wallet_db.py
@@ -104,21 +104,27 @@ for key in ['locked_in', 'fails', 'settles']:
 
 class WalletDB(JsonDB):
 
-    def __init__(self, raw, *, manual_upgrades: bool):
-        JsonDB.__init__(self, {})
-        self._manual_upgrades = manual_upgrades
-        self._called_after_upgrade_tasks = False
-        if raw:  # loading existing db
-            self.load_data(raw)
-            self.load_plugins()
-        else:  # creating new db
+    def __init__(self, data, *, manual_upgrades: bool):
+        JsonDB.__init__(self, data)
+        if not data:
+            # create new DB
             self.put('seed_version', FINAL_SEED_VERSION)
             self._add_db_creation_metadata()
             self._after_upgrade_tasks()
+        self._manual_upgrades = manual_upgrades
+        self._called_after_upgrade_tasks = False
+        if not self._manual_upgrades and self.requires_split():
+            raise WalletFileException("This wallet has multiple accounts and must be split")
+        if not self.requires_upgrade():
+            self._after_upgrade_tasks()
+        elif not self._manual_upgrades:
+            self.upgrade()
+        # load plugins that are conditional on wallet type
+        self.load_plugins()
 
     def load_data(self, s):
         try:
-            self.data = json.loads(s)
+            JsonDB.load_data(self, s)
         except Exception:
             try:
                 d = ast.literal_eval(s)
@@ -137,14 +143,6 @@ class WalletDB(JsonDB):
         if not isinstance(self.data, dict):
             raise WalletFileException("Malformed wallet file (not dict)")
 
-        if not self._manual_upgrades and self.requires_split():
-            raise WalletFileException("This wallet has multiple accounts and must be split")
-
-        if not self.requires_upgrade():
-            self._after_upgrade_tasks()
-        elif not self._manual_upgrades:
-            self.upgrade()
-
     def requires_split(self):
         d = self.get('accounts', {})
         return len(d) > 1
@@ -1583,21 +1581,6 @@ class WalletDB(JsonDB):
             return False
         return True
 
-    def write(self, storage: 'WalletStorage'):
-        with self.lock:
-            self._write(storage)
-
-    @profiler
-    def _write(self, storage: 'WalletStorage'):
-        if threading.current_thread().daemon:
-            self.logger.warning('daemon thread cannot write db')
-            return
-        if not self.modified():
-            return
-        json_str = self.dump(human_readable=not storage.is_encrypted())
-        storage.write(json_str)
-        self.set_modified(False)
-
     def is_ready_to_be_used_by_wallet(self):
         return not self.requires_upgrade() and self._called_after_upgrade_tasks