You've recently upgraded from IBM BPM 86 or earlier to one of the latest versions of IBM BAW and experiencing an issue related to stuck system lane tasks that might look like a regression from first sight.
Let's assume that some system lane task is calling web service. In a Web service call (outbound) something goes wrong and this task is stuck in the system lane. Instance status is Active, token is on the System Lane task. System Lane task is in Received state.
With such a stuck task what you normally do is - manually run them from Portal. E.g. you login with a system lane user (typically DE admin) and find a task in Portal and run it. All of this worked just fine in BPM 86 and previous versions but no longer seem to work in BAW 19003/2001.
Per the explanation I received from IBM Development team - if those stuck tasks are really system tasks, they are not supposed to run from Portal. This is by design.
In IBM BAW it appears there was a recent change introduced that only allows tasks that have a specific service type implementation to be launched in Process Portal, making all other service types treated as system tasks and preventing them from being launched in Process Portal. Only "CoachFlow" and "Human" or in other words, only heritage human service and client side human service tasks are allowed to run from Portal in IBM BAW by default.
If you have a similar use case or need as described in the above scenario where you need to launch a stuck system lane task from Portal then you can set the following Mashup config property:
to true under WAS admin console -> Resources -> Resource environment providers -> Mashups_ConfigService
You will need to restart Deployment environment and nodeagent(s) for the changes to be picked up.
After this you should be able to manually execute system lane tasks that presumably got stuck by deployment environment admin user user from Portal.
This property basically returns the previous behavior like it was in BPM 8.6.x.