diff --git a/src/validation.cpp b/src/validation.cpp
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -2159,14 +2159,6 @@
             warningMessages.push_back(strprintf(
                 _("%d of last 100 blocks have unexpected version"), nUpgraded));
         }
-        if (nUpgraded > 100 / 2) {
-            std::string strWarning =
-                _("Warning: Unknown block versions being mined! It's possible "
-                  "unknown rules are in effect");
-            // notify GetWarnings(), called by Qt and the JSON-RPC code to warn
-            // the user:
-            DoWarning(strWarning);
-        }
     }
     LogPrintf("%s: new best=%s height=%d version=0x%08x log2_work=%.8g tx=%lu "
               "date='%s' progress=%f cache=%.1fMiB(%utxo)",
diff --git a/test/functional/feature_notifications.py b/test/functional/feature_notifications.py
--- a/test/functional/feature_notifications.py
+++ b/test/functional/feature_notifications.py
@@ -72,30 +72,6 @@
         with open(self.tx_filename, 'r') as f:
             assert_equal(sorted(txids_rpc), sorted(f.read().splitlines()))
 
-        # Mine another 41 up-version blocks. -alertnotify should trigger on the 51st.
-        self.log.info("test -alertnotify for bip9")
-        self.nodes[1].generate(41)
-        self.sync_all()
-
-        # Give bitcoind 10 seconds to write the alert notification
-        wait_until(lambda: os.path.isfile(self.alert_filename)
-                   and os.path.getsize(self.alert_filename), timeout=10)
-
-        with open(self.alert_filename, 'r', encoding='utf8') as f:
-            alert_text = f.read()
-
-        # Mine more up-version blocks, should not get more alerts:
-        self.nodes[1].generate(2)
-        self.sync_all()
-
-        with open(self.alert_filename, 'r', encoding='utf8') as f:
-            alert_text2 = f.read()
-        os.remove(self.alert_filename)
-
-        self.log.info(
-            "-alertnotify should not continue notifying for more unknown version blocks")
-        assert_equal(alert_text, alert_text2)
-
         # Create an invalid chain and ensure the node warns.
         self.log.info("test -alertnotify for forked chain")
         fork_block = self.nodes[0].getbestblockhash()