Process instance got stuck in the middle

[ganeshr]

We have recently upgraded to latest version of  Activit 5.21 and after we are seeing an issue of process getting stuck in the exection.
This issue happened with older version and when we recycled the application then the process continued and created next task in the process.
Here is what we are seeing the issue,
We have a business process with 16 human tasks, the process went fine until the 10th step(human task) and after that it didn't created the 11th human task and when verified in execution table, it show like this in act_ru_execution table.

1   79fa0ac5-53fd-11e6-ad2e-020030001c32   11   79fa0ac5-53fd-11e6-ad2e-020030001c32         rail_access_process:3:39d5e0f6-0479-11e5-aad9-020030001c46      MarketingRealEstateTrackAgreementHumantask   1   0   1   0   1   2         

It should have created the MarketingRealEstateTrackAgreementHumantask   human task but it didnt and we lost the process instance and dont see a way to get it back again. Any help please ?

[jbarrez]

Without process definition xml (or relevant part) + what code gets executed it's hard to say.
How does one go from the 10th to the 11th step? A regular task complete?
Can you post the relevant bits of your process definition?

[ganeshr]

In most of the cases it was working, tasks are getting closed and creating next task in the process.
Yes, it's a regular task compelete using task service api provided by Actiivti, task getting completed but the next task not getting created and got stuck in the execution.

Find the attached process definition file. This is a subprocess which gets invoked from main process.
MtBusAssReviewHumantask was completed using activiti api, but the next task with name 'MtRealTrAgHumantask' is not get created and got stuck in the execution. 
Task names have been changed from the above post for confidentiality.

[ganeshr]

In addition to the above issue, we also see sometimes concurrent exception.

concurrent exception was happening with the new version of activiti 5.21, we never encountered this exception with earlier versions.

Unable to Inactivate Task(s) java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:188)

[martin_grofcik]

Hi Ganesh,

could you create jUnit test?
https://forums.activiti.org/content/sticky-how-write-unit-test

Regards
Martin