Env -Mendix: 10.12.1 -Database: MySQL Action -Domain 'MyApplcation' and 'MyApplicationThumbmail' association was in 1:1 relationship -Changed relationship N:1 as below Problem -Deployed Changes to Dev Server and Dev DB(MySQL) is Locked -recovered relationship between as 1:1 and db lock resolved -retried deployment and db locked again -restarted mysql db and issue resolved Question -Why DB lock problem happens? -Is there any way to avoid this error?