This commonly occurs when exporting views/triggers/procedures from one database or server to another as the user that created that object no longer exists.

#1449 - The user specified as a definer ('olduser'@'%') does not exist

You have two options:

1. Change the DEFINER

This is possibly easiest to do when initially importing your database objects, by removing any DEFINER statements from the dump. Changing the definer later is a more little tricky:

Run this SQL to generate the necessary ALTER statements:
SELECT CONCAT("ALTER DEFINER=`olduser`@`host` VIEW ", 
table_name, " AS ", view_definition, ";") 
FROM information_schema.views 
WHERE table_schema='your-database-name';
To change the definer for stored procedures:
UPDATE `mysql`.`proc` p SET definer = 'youruser@%' WHERE definer='olduser@%';
Be careful, because this will change all the definers for all databases.

2. Create the missing user

If you've found following error while using MySQL database:

 The user specified as a definer ('someuser'@'%') does not exist`.

Then you can solve it by using following : 

GRANT ALL ON *.* TO 'olduser'@'%' IDENTIFIED BY '12345678';
FLUSH PRIVILEGES;