Hello,

We have a lot of instances and want to migrate only failed instances to the new snapshot and do the re-try. 

Is it possible to migrate just a few instances from an old snapshot to a new one? Or is it not possible and all instances must be moved from the old snapshot to the new snapshot?

Version 21.0.3 of IBAW

Yes, you can migrate specific instances using the JS API - migrateWithContextTo(TWProcessAppSnapshot snapshot)

Migrates an instance and its context to the specified snapshot.

Documentation: https://www.ibm.com/docs/en/baw/19.x?topic=apis-javascript-api-in-processes-service-flows

So, you can use JS API to migrate just specific a single or multiple instances from snapshotA to snapshotB.

var twProcessApp = tw.system.model.processApp;
var twSS = twProcessApp.findSnapshotByName("Sanpshot name") ;
tw.system.currentProcessInstance.migrateWithContextTo(twSS);

Another example -

var instance = tw.system.findProcessInstanceByID(20449);
var snapshot = tw.system.model.findProcessAppByAcronym("IZT").findSnapshotByName("1.0.6.3");
instance.migrateWithContextTo(snapshot);

Hello Donata,

You can create a Process for migrating your process instances. This solution every time customizable and manageable...

Migrate Instance: 

var instance = tw.system.findProcessInstanceByID(tw.local.instanceList[tw.local.counter]);
var snapshot = tw.system.model.processApp.findSnapshotByID(tw.local.targetSnapshotId);
instance.migrateWithContextTo(snapshot);

log.info("Migrate Instance Process - InstanceId: " + tw.local.instanceList[tw.local.counter] + " migrated to " + tw.system.model.processAppSnapshot.acronym);
tw.local.counter++;

for using this process you can design a human services for UI or you can call Start Process method in REST Api

.../rest/bpm/wle/v1/process?action=start&bpdId=123&snapshotId=123&branchId=123&processAppId=123&parts=all