Summary

The Jira admin is unable to delete projects which is failing with the following error in the <jira-home>/log/atlassian-jira.log:

/secure/project/DeleteProject.jspa [c.a.jira.project.DefaultProjectManager] Exception removing issues
com.querydsl.core.QueryException: Caught SQLException for delete from customfieldvalue
where customfieldvalue.issue = ?
	at com.querydsl.sql.DefaultSQLExceptionTranslator.translate(DefaultSQLExceptionTranslator.java:50)
	...
Caused by: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction

Diagnosis

This type of error typically occurs when a transaction is waiting on row(s) of data to update which is already locked by another transaction. 

• Make sure the database tables are using InnoDB storage engine and READ-COMMITTED transaction isolation level.
• Increase the database server innodb_lock_wait_timeout variable to 500.
• Restart the MySQL database service and the Jira instance for the configuration to take place.
• Follow the resolution in the KB NullPointerException when Deleting a Custom Field.
• Run these queries below to double check the configuration:

show variables like '%wait_timeout%';
show variables like '%tx_isolation%';
SELECT @@GLOBAL.tx_isolation, @@tx_isolation;

Cause

If everything above is configured properly, the issue could be caused by incompatible 3rd-party listeners and custom fields. See JRASERVER-70522 - Updating custom field value during issue deletion can cause stuck threads for more information.

Solution

Enter Safe Mode and attempt to delete the projects.