diff --git a/py/webnotes/model/db_schema.py b/py/webnotes/model/db_schema.py
index 0de8cd8711..6d7882b413 100644
--- a/py/webnotes/model/db_schema.py
+++ b/py/webnotes/model/db_schema.py
@@ -200,15 +200,15 @@ class DbTable:
 			webnotes.conn.sql("alter table `%s` change `%s` `%s` %s" % (self.name, col.fieldname, col.fieldname, col.get_definition()))
 
 		for col in self.add_index:
-			webnotes.conn.sql("alter table `%s` add index `%s`(`%s`)" % (self.name, col.fieldname, col.fieldname))
+			# if index key not exists
+			if not webnotes.conn.sql("show index from `%s` where key_name = `%s`" % (self.name, col.fieldname)):
+				webnotes.conn.sql("alter table `%s` add index `%s`(`%s`)" % (self.name, col.fieldname, col.fieldname))
 
 		for col in self.drop_index:
 			if col.fieldname != 'name': # primary key
-				try:
+				# if index key exists
+				if webnotes.conn.sql("show index from `%s` where key_name = `%s`" % (self.name, col.fieldname)):
 					webnotes.conn.sql("alter table `%s` drop index `%s`" % (self.name, col.fieldname))
-				except _mysql_exceptions.OperationalError, e:
-					if e[0] != 1091: raise e
-
 
 		for col in self.set_default:
 			webnotes.conn.sql("alter table `%s` alter column `%s` set default %s" % (self.name, col.fieldname, '%s'), col.default)