diff --git a/jmclient/jmclient/blockchaininterface.py b/jmclient/jmclient/blockchaininterface.py
index d9e272a..777530a 100644
--- a/jmclient/jmclient/blockchaininterface.py
+++ b/jmclient/jmclient/blockchaininterface.py
@@ -168,8 +168,10 @@ class BitcoinCoreInterface(BlockchainInterface):
         if not blockchainInfo:
             # see note in BitcoinCoreInterface.rpc - here
             # we have to create this object before reactor start,
-            # so sys.exit *is* the right call:
-            sys.exit(EXIT_FAILURE)
+            # so reactor is not stopped, so we override the 'swallowing'
+            # of the Exception that happened in self.rpc():
+            raise JsonRpcConnectionError("RPC connection to Bitcoin Core "
+                                         "was not established successfully.")
         actualNet = blockchainInfo['chain']
 
         netmap = {'main': 'mainnet', 'test': 'testnet', 'regtest': 'regtest'}
diff --git a/jmclient/jmclient/wallet_service.py b/jmclient/jmclient/wallet_service.py
index 01b1e2c..25118af 100644
--- a/jmclient/jmclient/wallet_service.py
+++ b/jmclient/jmclient/wallet_service.py
@@ -41,16 +41,27 @@ class WalletService(Service):
         # the JM wallet object.
         self.bci = jm_single().bc_interface
 
+        # main loop used to check for transactions, instantiated
+        # after wallet is synced:
+        self.monitor_loop = None
+        self.wallet = wallet
+        self.synced = False
+
         # keep track of the quasi-real-time blockheight
         # (updated in main monitor loop)
         self.current_blockheight = None
         if self.bci is not None:
-            self.update_blockheight()
+            if not self.update_blockheight():
+                # this accounts for the unusual case
+                # where the application started up with
+                # a functioning blockchain interface, but
+                # that bci is now failing when we are starting
+                # the wallet service.
+                raise Exception("WalletService failed to start "
+                                "due to inability to query block height.")
         else:
             jlog.warning("No blockchain source available, " +
                 "wallet tools will not show correct balances.")
-        self.wallet = wallet
-        self.synced = False
 
         # Dicts of registered callbacks, by type
         # and then by txinfo, for events
@@ -119,7 +130,8 @@ class WalletService(Service):
         should *not* be restarted, instead a new
         WalletService instance should be created.
         """
-        self.monitor_loop.stop()
+        if self.monitor_loop:
+            self.monitor_loop.stop()
         self.wallet.close()
         super(WalletService, self).stopService()
 
diff --git a/scripts/joinmarket-qt.py b/scripts/joinmarket-qt.py
index 8cebd2d..7e42e48 100755
--- a/scripts/joinmarket-qt.py
+++ b/scripts/joinmarket-qt.py
@@ -1753,7 +1753,6 @@ class JMMainWindow(QMainWindow):
         # add information callbacks:
         self.wallet_service.add_restart_callback(self.restartWithMsg)
         self.wallet_service.autofreeze_warning_cb = self.autofreeze_warning_cb
-
         self.wallet_service.startService()
         self.syncmsg = ""
         self.walletRefresh = task.LoopingCall(self.updateWalletInfo)