diff --git a/mysql-test/main/grant5.result b/mysql-test/main/grant5.result
index 9407c17f52e..817a58e6ec2 100644
--- a/mysql-test/main/grant5.result
+++ b/mysql-test/main/grant5.result
@@ -461,6 +461,14 @@ create table mysql.host (host char(60) binary default '' not null, db char(64) b
 insert mysql.host values('10.5.0.0/255.255.0.0','','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','N');
 flush privileges;
 drop table mysql.host;
-#
 # End of 10.4 tests
 #
+# MDEV-18151: Skipped error returning for GRANT/SET PASSWORD
+#
+CREATE USER foo@localhost;
+GRANT FILE ON *.* TO foo@localhost IDENTIFIED VIA not_installed_plugin;
+ERROR HY000: Plugin 'not_installed_plugin' is not loaded
+DROP USER foo@localhost;
+CREATE USER foo@localhost IDENTIFIED VIA not_installed_plugin;
+ERROR HY000: Plugin 'not_installed_plugin' is not loaded
+# End of 10.5 tests
diff --git a/mysql-test/main/grant5.test b/mysql-test/main/grant5.test
index a7b82f454dc..48cc3087ffc 100644
--- a/mysql-test/main/grant5.test
+++ b/mysql-test/main/grant5.test
@@ -419,6 +419,20 @@ insert mysql.host values('10.5.0.0/255.255.0.0','','Y','Y','Y','Y','Y','Y','Y','
 flush privileges;
 drop table mysql.host;
 
---echo #
 --echo # End of 10.4 tests
+
 --echo #
+--echo # MDEV-18151: Skipped error returning for GRANT/SET PASSWORD
+--echo #
+
+CREATE USER foo@localhost;
+--error ER_PLUGIN_IS_NOT_LOADED
+GRANT FILE ON *.* TO foo@localhost IDENTIFIED VIA not_installed_plugin;
+
+# Cleanup
+DROP USER foo@localhost;
+
+--error ER_PLUGIN_IS_NOT_LOADED
+CREATE USER foo@localhost IDENTIFIED VIA not_installed_plugin;
+
+--echo # End of 10.5 tests
diff --git a/mysql-test/main/grant_plugin.result b/mysql-test/main/grant_plugin.result
new file mode 100644
index 00000000000..bf5b42b28b6
--- /dev/null
+++ b/mysql-test/main/grant_plugin.result
@@ -0,0 +1,17 @@
+#
+# MDEV-18151: Skipped error returning for GRANT/SET PASSWORD
+#
+install soname 'auth_0x0100';
+CREATE USER foo@localhost IDENTIFIED VIA auth_0x0100;
+uninstall plugin auth_0x0100;
+select Priv from mysql.global_priv where User = "foo" and host="localhost"
+into @priv;
+Warnings:
+Warning	1287	'<select expression> INTO <destination>;' is deprecated and will be removed in a future release. Please use 'SELECT <select list> INTO <destination> FROM...' instead
+SET PASSWORD FOR foo@localhost = "1111";
+ERROR HY000: Plugin 'auth_0x0100' is not loaded
+select Priv = @priv as "Nothing changed" from mysql.global_priv where User = "foo" and host="localhost";
+Nothing changed
+1
+DROP USER foo@localhost;
+# End of 10.5 tests
diff --git a/mysql-test/main/grant_plugin.test b/mysql-test/main/grant_plugin.test
new file mode 100644
index 00000000000..610176b0ce7
--- /dev/null
+++ b/mysql-test/main/grant_plugin.test
@@ -0,0 +1,24 @@
+
+--source include/not_embedded.inc
+
+if (!$AUTH_0X0100_SO) {
+  skip No auth_0x0100 plugin;
+}
+
+--echo #
+--echo # MDEV-18151: Skipped error returning for GRANT/SET PASSWORD
+--echo #
+
+install soname 'auth_0x0100';
+CREATE USER foo@localhost IDENTIFIED VIA auth_0x0100;
+uninstall plugin auth_0x0100;
+
+select Priv from mysql.global_priv where User = "foo" and host="localhost"
+into @priv;
+--error ER_PLUGIN_IS_NOT_LOADED
+SET PASSWORD FOR foo@localhost = "1111";
+select Priv = @priv as "Nothing changed" from mysql.global_priv where User = "foo" and host="localhost";
+
+DROP USER foo@localhost;
+
+--echo # End of 10.5 tests
diff --git a/mysql-test/main/plugin_auth.test b/mysql-test/main/plugin_auth.test
index 6912462066c..54d4b6637cb 100644
--- a/mysql-test/main/plugin_auth.test
+++ b/mysql-test/main/plugin_auth.test
@@ -31,7 +31,7 @@ connect(plug_con,localhost,plug,plug_dest);
 select USER(),CURRENT_USER();
 
 --echo ## test SET PASSWORD
-#--error ER_SET_PASSWORD_AUTH_PLUGIN
+# here we set for native password plugin
 SET PASSWORD = PASSWORD('plug_dest');
 
 connection default;
diff --git a/mysql-test/suite/plugins/r/multiauth.result b/mysql-test/suite/plugins/r/multiauth.result
index d1ecd600d84..07238b0940d 100644
--- a/mysql-test/suite/plugins/r/multiauth.result
+++ b/mysql-test/suite/plugins/r/multiauth.result
@@ -139,6 +139,7 @@ show create user mysqltest1;
 CREATE USER for mysqltest1@%
 CREATE USER `mysqltest1`@`%` IDENTIFIED VIA unix_socket OR mysql_native_password USING '*BFE3F4604CFD21E6595080A261D92EF0183B5971'
 set password for mysqltest1 = password('foobar');
+ERROR HY000: SET PASSWORD is ignored for users authenticating via unix_socket plugin
 show create user mysqltest1;
 CREATE USER for mysqltest1@%
 CREATE USER `mysqltest1`@`%` IDENTIFIED VIA unix_socket OR mysql_native_password USING '*9B500343BC52E2911172EB52AE5CF4847604C6E5'
diff --git a/mysql-test/suite/plugins/t/multiauth.test b/mysql-test/suite/plugins/t/multiauth.test
index 86c98a5d5c3..8f8a093e401 100644
--- a/mysql-test/suite/plugins/t/multiauth.test
+++ b/mysql-test/suite/plugins/t/multiauth.test
@@ -145,6 +145,7 @@ set password for mysqltest1 = password('foobar');
 show create user mysqltest1;
 alter user mysqltest1 identified via unix_socket OR mysql_native_password as password("some");
 show create user mysqltest1;
+--error ER_SET_PASSWORD_AUTH_PLUGIN
 set password for mysqltest1 = password('foobar');
 show create user mysqltest1;
 alter user mysqltest1 identified via unix_socket;
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index d0fa2ff9c1f..cd579be8010 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -2312,11 +2312,10 @@ static int set_user_auth(THD *thd, const LEX_CSTRING &user,
 
   mysql_mutex_assert_owner(&acl_cache->lock);
 
+  // check for SET PASSWORD
   if (!plugin)
   {
-    push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
-                        ER_PLUGIN_IS_NOT_LOADED,
-                        ER_THD(thd, ER_PLUGIN_IS_NOT_LOADED), plugin_name);
+    my_error(ER_PLUGIN_IS_NOT_LOADED, MYF(0), plugin_name);
     return ER_PLUGIN_IS_NOT_LOADED;
   }
 
@@ -2370,6 +2369,21 @@ static int set_user_auth(THD *thd, const LEX_CSTRING &user,
 
   res= 0;
 end:
+  switch(res)
+  {
+    case ER_OUTOFMEMORY:        // should be reported by my_malloc
+    case ER_NOT_VALID_PASSWORD: // should be reported by plugin
+    case ER_PASSWD_LENGTH:      // should be reported by plugin
+      DBUG_ASSERT(thd->is_error());
+      /* fall through*/
+    case 0:
+      break;
+    case ER_SET_PASSWORD_AUTH_PLUGIN:
+      my_error(res, MYF(0), plugin_name);
+      break;
+    default:
+      DBUG_ASSERT(0);
+  }
   if (unlock_plugin)
     plugin_unlock(thd, plugin);
   return res;