diff --git a/.github/workflows/test-stable.yml b/.github/workflows/test-stable.yml
index 024115a9..67334e42 100644
--- a/.github/workflows/test-stable.yml
+++ b/.github/workflows/test-stable.yml
@@ -233,7 +233,7 @@ jobs:
       uses: actions/checkout@v3
       with:
         path: ngircd
-        ref: rel-26.1
+        ref: 0714466af88d71d6c395629cd7fb624b099507d4
         repository: ngircd/ngircd
     - name: Build ngircd
       run: |
diff --git a/irctest/server_tests/chmodes/key.py b/irctest/server_tests/chmodes/key.py
index fd4c008e..26d60da5 100644
--- a/irctest/server_tests/chmodes/key.py
+++ b/irctest/server_tests/chmodes/key.py
@@ -44,8 +44,8 @@ def testKeyNormal(self):
 
     @pytest.mark.parametrize(
         "key",
-        ["passphrase with spaces", "long" * 100, ""],
-        ids=["spaces", "long", "empty"],
+        ["passphrase with spaces", "long" * 100, "", " "],
+        ids=["spaces", "long", "empty", "only-space"],
     )
     @cases.mark_specifications("RFC2812", "Modern")
     def testKeyValidation(self, key):
@@ -84,6 +84,8 @@ def testKeyValidation(self, key):
                 "ngIRCd does not validate channel keys: "
                 "https://github.com/ngircd/ngircd/issues/290"
             )
+        if key == " " and self.controller.software_name == "irc2":
+            pytest.xfail("irc2 rewrites non-empty keys that contain only spaces")
 
         self.connectClient("bar")
         self.joinChannel(1, "#chan")
diff --git a/irctest/server_tests/connection_registration.py b/irctest/server_tests/connection_registration.py
index 7399cb9c..a3d50384 100644
--- a/irctest/server_tests/connection_registration.py
+++ b/irctest/server_tests/connection_registration.py
@@ -5,6 +5,8 @@
 TODO: cross-reference Modern and RFC 2812 too
 """
 
+import time
+
 from irctest import cases
 from irctest.client_mock import ConnectionClosed
 from irctest.numerics import ERR_NEEDMOREPARAMS, ERR_PASSWDMISMATCH
@@ -133,7 +135,7 @@ def testNickCollision(self):
         self.assertNotEqual(
             m.command,
             "001",
-            "Received 001 after registering with the nick of a " "registered user.",
+            "Received 001 after registering with the nick of a registered user.",
         )
 
     def testEarlyNickCollision(self):
@@ -206,3 +208,58 @@ def testEmptyRealname(self):
             command=ERR_NEEDMOREPARAMS,
             params=[StrRe(r"(\*|foo)"), "USER", ANYSTR],
         )
+
+    def testNonutf8Realname(self):
+        self.addClient()
+        self.sendLine(1, "NICK foo")
+        line = b"USER username * * :i\xe8rc\xe9\r\n"
+        print("1 -> S (repr): " + repr(line))
+        self.clients[1].conn.sendall(line)
+        for _ in range(10):
+            time.sleep(1)
+            d = self.clients[1].conn.recv(10000)
+            self.assertTrue(d, "Server closed connection")
+            print("S -> 1 (repr): " + repr(d))
+            if b" 001 " in d:
+                break
+            if b"ERROR " in d or b" FAIL " in d:
+                # Rejected; nothing more to test.
+                return
+            for line in d.split(b"\r\n"):
+                if line.startswith(b"PING "):
+                    line = line.replace(b"PING", b"PONG") + b"\r\n"
+                    print("1 -> S (repr): " + repr(line))
+                    self.clients[1].conn.sendall(line)
+        else:
+            self.assertTrue(False, "stuck waiting")
+        self.sendLine(1, "WHOIS foo")
+        time.sleep(3)  # for ngIRCd
+        d = self.clients[1].conn.recv(10000)
+        print("S -> 1 (repr): " + repr(d))
+        self.assertIn(b"username", d)
+
+    def testNonutf8Username(self):
+        self.addClient()
+        self.sendLine(1, "NICK foo")
+        self.sendLine(1, "USER 😊😊😊😊😊😊😊😊😊😊 * * :realname")
+        for _ in range(10):
+            time.sleep(1)
+            d = self.clients[1].conn.recv(10000)
+            self.assertTrue(d, "Server closed connection")
+            print("S -> 1 (repr): " + repr(d))
+            if b" 001 " in d:
+                break
+            if b" 468" in d or b"ERROR " in d:
+                # Rejected; nothing more to test.
+                return
+            for line in d.split(b"\r\n"):
+                if line.startswith(b"PING "):
+                    line = line.replace(b"PING", b"PONG") + b"\r\n"
+                    print("1 -> S (repr): " + repr(line))
+                    self.clients[1].conn.sendall(line)
+        else:
+            self.assertTrue(False, "stuck waiting")
+        self.sendLine(1, "WHOIS foo")
+        d = self.clients[1].conn.recv(10000)
+        print("S -> 1 (repr): " + repr(d))
+        self.assertIn(b"realname", d)
diff --git a/irctest/server_tests/messages.py b/irctest/server_tests/messages.py
index 441446df..c0f4ec0a 100644
--- a/irctest/server_tests/messages.py
+++ b/irctest/server_tests/messages.py
@@ -53,6 +53,28 @@ def testPrivmsgNonexistentUser(self):
         # ERR_NOSUCHNICK: 401 <sender> <recipient> :No such nick
         self.assertMessageMatch(msg, command="401", params=["foo", "bar", ANYSTR])
 
+    @cases.mark_specifications("RFC1459", "RFC2812", "Modern")
+    @cases.xfailIfSoftware(
+        ["irc2"],
+        "replies with ERR_NEEDMOREPARAMS instead of ERR_NOTEXTTOSEND",
+    )
+    def testEmptyPrivmsg(self):
+        self.connectClient("foo")
+        self.sendLine(1, "JOIN #chan")
+        self.getMessages(1)  # synchronize
+        self.connectClient("bar")
+        self.sendLine(2, "JOIN #chan")
+        self.getMessages(2)  # synchronize
+        self.getMessages(1)  # synchronize
+        self.sendLine(1, "PRIVMSG #chan :")
+
+        self.assertMessageMatch(
+            self.getMessage(1),
+            command="412",  # ERR_NOTEXTTOSEND
+            params=["foo", ANYSTR],
+        )
+        self.assertEqual(self.getMessages(2), [])
+
 
 class NoticeTestCase(cases.BaseServerTestCase):
     @cases.mark_specifications("RFC1459", "RFC2812")
diff --git a/irctest/server_tests/utf8.py b/irctest/server_tests/utf8.py
index bb5e77da..12ac1298 100644
--- a/irctest/server_tests/utf8.py
+++ b/irctest/server_tests/utf8.py
@@ -46,3 +46,38 @@ def testUtf8Validation(self):
 
         if m.command in ("FAIL", "WARN"):
             self.assertMessageMatch(m, params=["PRIVMSG", "INVALID_UTF8", ANYSTR])
+
+    def testNonutf8Realname(self):
+        self.connectClient("foo")
+        if "UTF8ONLY" not in self.server_support:
+            raise runner.IsupportTokenNotSupported("UTF8ONLY")
+
+        self.addClient()
+        self.sendLine(2, "NICK foo")
+        self.clients[2].conn.sendall(b"USER username * * :i\xe8rc\xe9\r\n")
+
+        d = self.clients[2].conn.recv(1024)
+        if b" FAIL " in d or b" 468 " in d:  # ERR_INVALIDUSERNAME
+            return  # nothing more to test
+        self.assertIn(b" 001 ", d)
+
+        self.sendLine(2, "WHOIS foo")
+        self.getMessages(2)
+
+    def testNonutf8Username(self):
+        self.connectClient("foo")
+        if "UTF8ONLY" not in self.server_support:
+            raise runner.IsupportTokenNotSupported("UTF8ONLY")
+
+        self.addClient()
+        self.sendLine(2, "NICK foo")
+        self.sendLine(2, "USER 😊😊😊😊😊😊😊😊😊😊 * * :realname")
+        m = self.getRegistrationMessage(2)
+        if m.command in ("FAIL", "468"):  # ERR_INVALIDUSERNAME
+            return  # nothing more to test
+        self.assertMessageMatch(
+            m,
+            command="001",
+        )
+        self.sendLine(2, "WHOIS foo")
+        self.getMessages(2)
diff --git a/workflows.yml b/workflows.yml
index 8c187dad..1033a19f 100644
--- a/workflows.yml
+++ b/workflows.yml
@@ -235,7 +235,7 @@ software:
         name: ngircd
         repository: ngircd/ngircd
         refs:
-            stable: rel-26.1
+            stable: 0714466af88d71d6c395629cd7fb624b099507d4 # two years ahead of rel-26.1
             release: null
             devel: master
             devel_release: null