diff --git a/src/box/sql/build.c b/src/box/sql/build.c
index c39ac281113a279b858776513da285778a1422a0..8a42453c89c1ed05675934417121b77881b04980 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -653,7 +653,12 @@ sqlite3AddColumn(Parse * pParse, Token * pName, Token * pType)
 	struct field_def *column_def = &p->def->fields[p->def->field_count];
 	memcpy(column_def, &field_def_default, sizeof(field_def_default));
 	column_def->name = z;
-	column_def->nullable_action = ON_CONFLICT_ACTION_NONE;
+	/*
+	 * Marker on_conflict_action_MAX is used to detect
+	 * attempts to define NULL multiple time or to detect
+	 * invalid primary key definition.
+	 */
+	column_def->nullable_action = on_conflict_action_MAX;
 	column_def->is_nullable = true;
 
 	if (pType->n == 0) {
@@ -688,22 +693,30 @@ sqlite3AddColumn(Parse * pParse, Token * pName, Token * pType)
 	pParse->constraintName.n = 0;
 }
 
-/*
- * This routine is called by the parser while in the middle of
- * parsing a CREATE TABLE statement.  A "NOT NULL" constraint has
- * been seen on a column.  This routine sets the notNull flag on
- * the column currently under construction.
- */
 void
-sqlite3AddNotNull(Parse * pParse, int onError)
+sql_column_add_nullable_action(struct Parse *parser,
+			       enum on_conflict_action nullable_action)
 {
-	Table *p;
-	p = pParse->pNewTable;
-	if (p == 0 || NEVER(p->def->field_count < 1))
+	struct Table *p = parser->pNewTable;
+	if (p == NULL || NEVER(p->def->field_count < 1))
 		return;
-	p->def->fields[p->def->field_count - 1].nullable_action = (u8)onError;
-	p->def->fields[p->def->field_count - 1].is_nullable =
-		action_is_nullable(onError);
+	struct field_def *field = &p->def->fields[p->def->field_count - 1];
+	if (field->nullable_action != on_conflict_action_MAX &&
+	    nullable_action != ON_CONFLICT_ACTION_DEFAULT) {
+		/* Prevent defining nullable_action many times. */
+		const char *err_msg =
+			tt_sprintf("NULL declaration for column '%s' of table "
+				   "'%s' has been already set to '%s'",
+				   field->name, p->def->name,
+				   on_conflict_action_strs[field->
+							   nullable_action]);
+		diag_set(ClientError, ER_SQL, err_msg);
+		parser->rc = SQL_TARANTOOL_ERROR;
+		parser->nErr++;
+		return;
+	}
+	field->nullable_action = nullable_action;
+	field->is_nullable = action_is_nullable(nullable_action);
 }
 
 /*
@@ -849,6 +862,23 @@ sqlite3AddDefaultValue(Parse * pParse, ExprSpan * pSpan)
 	sql_expr_delete(db, pSpan->pExpr, false);
 }
 
+static int
+field_def_create_for_pk(struct Parse *parser, struct field_def *field,
+			const char *space_name)
+{
+	if (field->nullable_action != ON_CONFLICT_ACTION_ABORT &&
+	    field->nullable_action != ON_CONFLICT_ACTION_DEFAULT &&
+	    field->nullable_action != on_conflict_action_MAX) {
+		diag_set(ClientError, ER_NULLABLE_PRIMARY, space_name);
+		parser->rc = SQL_TARANTOOL_ERROR;
+		parser->nErr++;
+		return -1;
+	} else if (field->nullable_action == on_conflict_action_MAX) {
+		field->nullable_action = ON_CONFLICT_ACTION_ABORT;
+		field->is_nullable = false;
+	}
+	return 0;
+}
 
 /*
  * Designate the PRIMARY KEY for the table.  pList is a list of names
@@ -944,12 +974,11 @@ sqlite3AddPrimaryKey(Parse * pParse,	/* Parsing context */
 		pList = 0;
 	}
 
- 	/* Mark every PRIMARY KEY column as NOT NULL. */
+	/* Mark every PRIMARY KEY column as NOT NULL. */
 	for (uint32_t i = 0; i < pTab->def->field_count; i++) {
 		if (pTab->aCol[i].is_primkey) {
-			pTab->def->fields[i].nullable_action
-				= ON_CONFLICT_ACTION_ABORT;
-			pTab->def->fields[i].is_nullable = false;
+			field_def_create_for_pk(pParse, &pTab->def->fields[i],
+						pTab->def->name);
 		}
 	}
 primary_key_exit:
@@ -1611,6 +1640,15 @@ sqlite3EndTable(Parse * pParse,	/* Parse context */
 		}
 	}
 
+	/* Set default on_nullable action if required. */
+	struct field_def *field = p->def->fields;
+	for (uint32_t i = 0; i < p->def->field_count; ++i, ++field) {
+		if (field->nullable_action == on_conflict_action_MAX) {
+			field->nullable_action = ON_CONFLICT_ACTION_NONE;
+			field->is_nullable = true;
+		}
+	}
+
 	if (check_on_conflict_replace_entries(p)) {
 		sqlite3ErrorMsg(pParse,
 				"only PRIMARY KEY constraint can "
diff --git a/src/box/sql/parse.y b/src/box/sql/parse.y
index 0c510f565a7a6c318d1b2bae139624043d0cb833..1e3f96ec6e851e0a4457bbc8e47e0d19337713ae 100644
--- a/src/box/sql/parse.y
+++ b/src/box/sql/parse.y
@@ -272,8 +272,13 @@ ccons ::= DEFAULT id(X).              {
 // In addition to the type name, we also care about the primary key and
 // UNIQUE constraints.
 //
-ccons ::= NULL onconf.
-ccons ::= NOT NULL onconf(R).    {sqlite3AddNotNull(pParse, R);}
+ccons ::= NULL onconf(R).        {
+    sql_column_add_nullable_action(pParse, ON_CONFLICT_ACTION_NONE);
+    /* Trigger nullability mismatch error if required. */
+    if (R != ON_CONFLICT_ACTION_DEFAULT)
+        sql_column_add_nullable_action(pParse, R);
+}
+ccons ::= NOT NULL onconf(R).    {sql_column_add_nullable_action(pParse, R);}
 ccons ::= PRIMARY KEY sortorder(Z) onconf(R) autoinc(I).
                                  {sqlite3AddPrimaryKey(pParse,0,R,I,Z);}
 ccons ::= UNIQUE onconf(R).      {sql_create_index(pParse,0,0,0,R,0,0,
diff --git a/src/box/sql/sqliteInt.h b/src/box/sql/sqliteInt.h
index 07e7829e5e94bacd3bf75bce5dafccca9ce19ab8..62a86fc550bd7df507f005534b5ff100f1ac660c 100644
--- a/src/box/sql/sqliteInt.h
+++ b/src/box/sql/sqliteInt.h
@@ -3516,7 +3516,22 @@ Table *sqlite3ResultSetOfSelect(Parse *, Select *);
 Index *sqlite3PrimaryKeyIndex(Table *);
 void sqlite3StartTable(Parse *, Token *, int);
 void sqlite3AddColumn(Parse *, Token *, Token *);
-void sqlite3AddNotNull(Parse *, int);
+
+/**
+ * This routine is called by the parser while in the middle of
+ * parsing a CREATE TABLE statement.  A "NOT NULL" constraint has
+ * been seen on a column.  This routine sets the is_nullable flag
+ * on the column currently under construction.
+ * If nullable_action has been already set, this function raises
+ * an error.
+ *
+ * @param parser SQL Parser object.
+ * @param nullable_action on_conflict_action value.
+ */
+void
+sql_column_add_nullable_action(struct Parse *parser,
+			       enum on_conflict_action nullable_action);
+
 void sqlite3AddPrimaryKey(Parse *, ExprList *, int, int, enum sort_order);
 
 /**
diff --git a/test/sql/on-conflict.result b/test/sql/on-conflict.result
index b4772d80e2e96cc276adc2ad0e4db18087abc5e4..eed06d582ba6d0c057f9aeb1832e9116aea2ad63 100644
--- a/test/sql/on-conflict.result
+++ b/test/sql/on-conflict.result
@@ -99,3 +99,23 @@ box.sql.execute('DROP TABLE t1')
 box.sql.execute('DROP TABLE t2')
 ---
 ...
+--
+-- gh-3473: Primary key can't be declared with NULL.
+--
+box.sql.execute('CREATE TABLE te17 (s1 INT NULL PRIMARY KEY NOT NULL);')
+---
+- error: Primary index of the space 'TE17' can not contain nullable parts
+...
+box.sql.execute('CREATE TABLE te17 (s1 INT NULL PRIMARY KEY);')
+---
+- error: Primary index of the space 'TE17' can not contain nullable parts
+...
+box.sql.execute("CREATE TABLE test (a int PRIMARY KEY, b int NULL ON CONFLICT IGNORE);")
+---
+- error: 'SQL error: NULL declaration for column ''B'' of table ''TEST'' has been
+    already set to ''none'''
+...
+box.sql.execute("CREATE TABLE test (a int, b int NULL, c int, PRIMARY KEY(a, b, c))")
+---
+- error: Primary index of the space 'TEST' can not contain nullable parts
+...
diff --git a/test/sql/on-conflict.test.lua b/test/sql/on-conflict.test.lua
index b6d92f7c352bb780b7a3cda4e99f93e9cd9e3516..347245a8c46c07c8b2dd9e1ed3f7e292e4146d14 100644
--- a/test/sql/on-conflict.test.lua
+++ b/test/sql/on-conflict.test.lua
@@ -38,3 +38,11 @@ box.sql.execute('DROP TABLE p')
 box.sql.execute('DROP TABLE e')
 box.sql.execute('DROP TABLE t1')
 box.sql.execute('DROP TABLE t2')
+
+--
+-- gh-3473: Primary key can't be declared with NULL.
+--
+box.sql.execute('CREATE TABLE te17 (s1 INT NULL PRIMARY KEY NOT NULL);')
+box.sql.execute('CREATE TABLE te17 (s1 INT NULL PRIMARY KEY);')
+box.sql.execute("CREATE TABLE test (a int PRIMARY KEY, b int NULL ON CONFLICT IGNORE);")
+box.sql.execute("CREATE TABLE test (a int, b int NULL, c int, PRIMARY KEY(a, b, c))")