I have been doing some log analysis regarding this foreign key error. According to hibernate logs, swimlanes instances are deleted long before module instance is being deleted (as expected). However, it seems that not all swimlanes instances are deleted (at least for for my case). In the case that I have been working with I realized hibernate logged 5 delete statements. 299627 [http-8080-Processor22] DEBUG 2007-08-23 11:26:49,338 org.hibernate.jdbc.AbstractBatcher:logOpenPreparedStatement[311] about to open PreparedStatement (open PreparedStatements: 0, globally: 0) 299627 [http-8080-Processor22] DEBUG 2007-08-23 11:26:49,338 org.hibernate.jdbc.AbstractBatcher:log[346] delete from JBPM_SWIMLANEINSTANCE where ID_=? 299628 [http-8080-Processor22] DEBUG 2007-08-23 11:26:49,339 org.hibernate.jdbc.AbstractBatcher:prepareBatchStatement[175] reusing prepared statement 299628 [http-8080-Processor22] DEBUG 2007-08-23 11:26:49,339 org.hibernate.jdbc.AbstractBatcher:log[346] delete from JBPM_SWIMLANEINSTANCE where ID_=? 299629 [http-8080-Processor22] DEBUG 2007-08-23 11:26:49,340 org.hibernate.jdbc.AbstractBatcher:prepareBatchStatement[175] reusing prepared statement 299629 [http-8080-Processor22] DEBUG 2007-08-23 11:26:49,340 org.hibernate.jdbc.AbstractBatcher:log[346] delete from JBPM_SWIMLANEINSTANCE where ID_=? 299629 [http-8080-Processor22] DEBUG 2007-08-23 11:26:49,340 org.hibernate.jdbc.AbstractBatcher:prepareBatchStatement[175] reusing prepared statement 299630 [http-8080-Processor22] DEBUG 2007-08-23 11:26:49,341 org.hibernate.jdbc.AbstractBatcher:log[346] delete from JBPM_SWIMLANEINSTANCE where ID_=? 299630 [http-8080-Processor22] DEBUG 2007-08-23 11:26:49,341 org.hibernate.jdbc.AbstractBatcher:prepareBatchStatement[175] reusing prepared statement 299631 [http-8080-Processor22] DEBUG 2007-08-23 11:26:49,342 org.hibernate.jdbc.AbstractBatcher:log[346] delete from JBPM_SWIMLANEINSTANCE where ID_=? 299631 [http-8080-Processor22] DEBUG 2007-08-23 11:26:49,342 org.hibernate.jdbc.BatchingBatcher:doExecuteBatch[55] Executing batch size: 5 However, there were total of 6 swimlane instances in the jbpm_swimlaneinstance table (for the test case). +-----+-----------------------+------------------------------+-----------+-------------------+ | ID_ | NAME_ | ACTORID_ | SWIMLANE_ | TASKMGMTINSTANCE_ | +-----+-----------------------+------------------------------+-----------+-------------------+ | 38 | originator | xx(a)xx.com | 440 | 33 | | 39 | charge code approvers | xx(a)xx.com | 441 | 33 | | 40 | quality | xx(a)xx.com | 444 | 33 | | 41 | procurement lead | xx(a)xx.com | 439 | 33 | | 49 | charge code approvers | xx(a)xx.com | 441 | 33 | | 50 | buyer | xx(a)xx.com | 442 | 33 | +-----+-----------------------+------------------------------+-----------+-------------------+ JBPM then tried to delete module instance which basically threw the exception in question. I think I need to figure out why that swimlane instance is not deleted. If you have any recommendations or ideas. Please let me know. thanks View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4077418#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...