diff --git a/client/client_priv.h b/client/client_priv.h
index 832589f015c..c205d07c34c 100644
--- a/client/client_priv.h
+++ b/client/client_priv.h
@@ -80,6 +80,6 @@ enum options_client
   OPT_MYSQL_REPLACE_INTO, OPT_BASE64_OUTPUT, OPT_SERVER_ID,
   OPT_FIX_TABLE_NAMES, OPT_FIX_DB_NAMES, OPT_SSL_VERIFY_SERVER_CERT,
   OPT_DEBUG_INFO, OPT_DEBUG_CHECK, OPT_COLUMN_TYPES, OPT_ERROR_LOG_FILE,
-  OPT_DUMP_DATE,
-  OPT_WRITE_BINLOG, OPT_MAX_CLIENT_OPTION
+  OPT_WRITE_BINLOG, OPT_DUMP_DATE,
+  OPT_MAX_CLIENT_OPTION
 };
diff --git a/mysql-test/r/information_schema.result b/mysql-test/r/information_schema.result
index cd0f9a7a172..2d8ff8d433f 100644
--- a/mysql-test/r/information_schema.result
+++ b/mysql-test/r/information_schema.result
@@ -1470,6 +1470,10 @@ f7	datetime	NO		NULL
 f8	datetime	YES		2006-01-01 00:00:00	
 drop table t1;
 End of 5.0 tests.
+show fields from information_schema.TABLE_NAMES;
+ERROR 42S02: Unknown table 'TABLE_NAMES' in information_schema
+show keys from information_schema.TABLE_NAMES;
+ERROR 42S02: Unknown table 'TABLE_NAMES' in information_schema
 select * from information_schema.engines WHERE ENGINE="MyISAM";
 ENGINE	SUPPORT	COMMENT	TRANSACTIONS	XA	SAVEPOINTS
 MyISAM	DEFAULT	Default engine as of MySQL 3.23 with great performance	NO	NO	NO
diff --git a/mysql-test/r/olap.result b/mysql-test/r/olap.result
index 67c45b698ce..63c9590401c 100644
--- a/mysql-test/r/olap.result
+++ b/mysql-test/r/olap.result
@@ -715,3 +715,14 @@ a	SUM(a)
 4	4
 NULL	14
 DROP TABLE t1;
+#
+# Bug#31095: Unexpected NULL constant caused server crash.
+#
+create table t1(a int);
+insert into t1 values (1),(2),(3);
+select count(a) from t1 group by null with rollup;
+count(a)
+3
+3
+drop table t1;
+##############################################################
diff --git a/mysql-test/t/information_schema.test b/mysql-test/t/information_schema.test
index c2c0f79d66b..6edc2353fc0 100644
--- a/mysql-test/t/information_schema.test
+++ b/mysql-test/t/information_schema.test
@@ -1090,6 +1090,15 @@ show columns from t1;
 drop table t1;
 
 --echo End of 5.0 tests.
+
+#
+# Bug#30079 A check for "hidden" I_S tables is flawed
+#
+--error 1109
+show fields from information_schema.TABLE_NAMES;
+--error 1109
+show keys from information_schema.TABLE_NAMES;
+
 #
 # Show engines
 #
diff --git a/mysql-test/t/olap.test b/mysql-test/t/olap.test
index 05934bff492..1ac99d9c39f 100644
--- a/mysql-test/t/olap.test
+++ b/mysql-test/t/olap.test
@@ -358,3 +358,12 @@ SELECT * FROM (SELECT a, SUM(a) FROM t1 GROUP BY a WITH ROLLUP) as t;
 
 DROP TABLE t1;
 
+--echo #
+--echo # Bug#31095: Unexpected NULL constant caused server crash.
+--echo #
+create table t1(a int);
+insert into t1 values (1),(2),(3);
+select count(a) from t1 group by null with rollup;
+drop table t1;
+--echo ##############################################################
+
diff --git a/sql/item_func.h b/sql/item_func.h
index 602c1c86f01..8800692f192 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -756,6 +756,8 @@ public:
     collation= args[0]->collation;
     max_length= args[0]->max_length;
     decimals=args[0]->decimals; 
+    /* The item could be a NULL constant. */
+    null_value= args[0]->null_value;
   }
 };
 
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index ae347bebb47..4204e9ec881 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -5766,7 +5766,12 @@ TABLE_LIST *st_select_lex::add_table_to_list(THD *thd,
     ST_SCHEMA_TABLE *schema_table= find_schema_table(thd, ptr->table_name);
     if (!schema_table ||
         (schema_table->hidden && 
-         (sql_command_flags[lex->sql_command] & CF_STATUS_COMMAND) == 0))
+         ((sql_command_flags[lex->sql_command] & CF_STATUS_COMMAND) == 0 || 
+          /*
+            this check is used for show columns|keys from I_S hidden table
+          */
+          lex->sql_command == SQLCOM_SHOW_FIELDS ||
+          lex->sql_command == SQLCOM_SHOW_KEYS)))
     {
       my_error(ER_UNKNOWN_TABLE, MYF(0),
                ptr->table_name, INFORMATION_SCHEMA_NAME.str);
diff --git a/tests/mysql_client_test.c b/tests/mysql_client_test.c
index 50e0511ae96..267b8aff699 100644
--- a/tests/mysql_client_test.c
+++ b/tests/mysql_client_test.c
@@ -16035,13 +16035,15 @@ static void test_bug21635()
   {
     field= mysql_fetch_field_direct(result, i);
     if (!opt_silent)
-      printf("%s -> %s ... ", expr[i * 2], field->name);
+      if (!opt_silent)
+        printf("%s -> %s ... ", expr[i * 2], field->name);
     fflush(stdout);
     DIE_UNLESS(field->db[0] == 0 && field->org_table[0] == 0 &&
                field->table[0] == 0 && field->org_name[0] == 0);
     DIE_UNLESS(strcmp(field->name, expr[i * 2 + 1]) == 0);
     if (!opt_silent)
-      puts("OK");
+      if (!opt_silent)
+        puts("OK");
   }
 
     mysql_free_result(result);