diff --git a/django/contrib/auth/hashers.py b/django/contrib/auth/hashers.py
index 9946014ad2..cac11dfd4c 100644
--- a/django/contrib/auth/hashers.py
+++ b/django/contrib/auth/hashers.py
@@ -689,7 +689,8 @@ class UnsaltedSHA1PasswordHasher(BasePasswordHasher):
         return ''
 
     def encode(self, password, salt):
-        assert salt == ''
+        if salt != '':
+            raise ValueError('salt must be empty.')
         hash = hashlib.sha1(password.encode()).hexdigest()
         return 'sha1$$%s' % hash
 
@@ -733,7 +734,8 @@ class UnsaltedMD5PasswordHasher(BasePasswordHasher):
         return ''
 
     def encode(self, password, salt):
-        assert salt == ''
+        if salt != '':
+            raise ValueError('salt must be empty.')
         return hashlib.md5(password.encode()).hexdigest()
 
     def decode(self, encoded):
@@ -774,9 +776,11 @@ class CryptPasswordHasher(BasePasswordHasher):
 
     def encode(self, password, salt):
         crypt = self._load_library()
-        assert len(salt) == 2
+        if len(salt) != 2:
+            raise ValueError('salt must be of length 2.')
         hash = crypt.crypt(password, salt)
-        assert hash is not None  # A platform like OpenBSD with a dummy crypt module.
+        if hash is None:  # A platform like OpenBSD with a dummy crypt module.
+            raise TypeError('hash must be provided.')
         # we don't need to store the salt, but Django used to do this
         return '%s$%s$%s' % (self.algorithm, '', hash)
 
diff --git a/tests/auth_tests/test_hashers.py b/tests/auth_tests/test_hashers.py
index 81234a44f0..dda64971ba 100644
--- a/tests/auth_tests/test_hashers.py
+++ b/tests/auth_tests/test_hashers.py
@@ -143,6 +143,13 @@ class TestUtilsHashPass(SimpleTestCase):
         self.assertTrue(check_password('', blank_encoded))
         self.assertFalse(check_password(' ', blank_encoded))
 
+    @override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.UnsaltedMD5PasswordHasher'])
+    def test_unsalted_md5_encode_invalid_salt(self):
+        hasher = get_hasher('unsalted_md5')
+        msg = 'salt must be empty.'
+        with self.assertRaisesMessage(ValueError, msg):
+            hasher.encode('password', salt='salt')
+
     @override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.UnsaltedSHA1PasswordHasher'])
     def test_unsalted_sha1(self):
         encoded = make_password('lètmein', '', 'unsalted_sha1')
@@ -161,6 +168,13 @@ class TestUtilsHashPass(SimpleTestCase):
         self.assertTrue(check_password('', blank_encoded))
         self.assertFalse(check_password(' ', blank_encoded))
 
+    @override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.UnsaltedSHA1PasswordHasher'])
+    def test_unsalted_sha1_encode_invalid_salt(self):
+        hasher = get_hasher('unsalted_sha1')
+        msg = 'salt must be empty.'
+        with self.assertRaisesMessage(ValueError, msg):
+            hasher.encode('password', salt='salt')
+
     @skipUnless(crypt, "no crypt module to generate password.")
     @override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.CryptPasswordHasher'])
     def test_crypt(self):
@@ -177,6 +191,23 @@ class TestUtilsHashPass(SimpleTestCase):
         self.assertTrue(check_password('', blank_encoded))
         self.assertFalse(check_password(' ', blank_encoded))
 
+    @skipUnless(crypt, 'no crypt module to generate password.')
+    @override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.CryptPasswordHasher'])
+    def test_crypt_encode_invalid_salt(self):
+        hasher = get_hasher('crypt')
+        msg = 'salt must be of length 2.'
+        with self.assertRaisesMessage(ValueError, msg):
+            hasher.encode('password', salt='a')
+
+    @skipUnless(crypt, 'no crypt module to generate password.')
+    @override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.CryptPasswordHasher'])
+    def test_crypt_encode_invalid_hash(self):
+        hasher = get_hasher('crypt')
+        msg = 'hash must be provided.'
+        with mock.patch('crypt.crypt', return_value=None):
+            with self.assertRaisesMessage(TypeError, msg):
+                hasher.encode('password', salt='ab')
+
     @skipUnless(bcrypt, "bcrypt not installed")
     def test_bcrypt_sha256(self):
         encoded = make_password('lètmein', hasher='bcrypt_sha256')