diff --git a/electrum/invoices.py b/electrum/invoices.py
index 6105ab4a8..c9e9584a3 100644
--- a/electrum/invoices.py
+++ b/electrum/invoices.py
@@ -118,7 +118,7 @@ class OnchainInvoice(Invoice):
     outputs = attr.ib(kw_only=True, converter=_decode_outputs)  # type: List[PartialTxOutput]
     bip70 = attr.ib(type=str, kw_only=True)  # type: Optional[str]
     requestor = attr.ib(type=str, kw_only=True)  # type: Optional[str]
-    height = attr.ib(type=int, default=0, kw_only=True, validator=attr.validators.instance_of(int))
+    height = attr.ib(type=int, kw_only=True, validator=attr.validators.instance_of(int))
 
     def get_address(self) -> str:
         """returns the first address, to be displayed in GUI"""
diff --git a/electrum/wallet_db.py b/electrum/wallet_db.py
index fc792a8eb..49bc11ab1 100644
--- a/electrum/wallet_db.py
+++ b/electrum/wallet_db.py
@@ -52,7 +52,7 @@ if TYPE_CHECKING:
 
 OLD_SEED_VERSION = 4        # electrum versions < 2.0
 NEW_SEED_VERSION = 11       # electrum versions >= 2.0
-FINAL_SEED_VERSION = 32     # electrum >= 2.7 will set this to prevent
+FINAL_SEED_VERSION = 33     # electrum >= 2.7 will set this to prevent
                             # old versions from overwriting new format
 
 
@@ -180,6 +180,7 @@ class WalletDB(JsonDB):
         self._convert_version_30()
         self._convert_version_31()
         self._convert_version_32()
+        self._convert_version_33()
         self.put('seed_version', FINAL_SEED_VERSION)  # just to be sure
 
         self._after_upgrade_tasks()
@@ -695,6 +696,20 @@ class WalletDB(JsonDB):
         self.data['invoices'] = invoices_new
         self.data['seed_version'] = 32
 
+    def _convert_version_33(self):
+        if not self._is_upgrade_method_needed(32, 32):
+            return
+
+        from .invoices import PR_TYPE_ONCHAIN
+        requests = self.data.get('payment_requests', {})
+        invoices = self.data.get('invoices', {})
+        for d in [invoices, requests]:
+            for key, item in list(d.items()):
+                if item['type'] == PR_TYPE_ONCHAIN:
+                    item['height'] = item.get('height') or 0
+
+        self.data['seed_version'] = 33
+
     def _convert_imported(self):
         if not self._is_upgrade_method_needed(0, 13):
             return