The bad thing about this bug is, that it's only happening on rare occasions so it's not really reproducible. It already happend when the affected task was created but we thought we could work around it by using ContentUtil.changeNodeType() instead of Node.setPrimaryType(). As this did not really fix the problem, we should now analyze in detail and get rid of it.

Stacktrace:
[INFO] [talledLocalContainer] info.magnolia.module.delta.TaskExecutionException: Could not convert contentnodes to DAM format. /demo-project/img/bk/Opener/v-light-3: mandatory child node

content does not exist
[INFO] [talledLocalContainer] at info.magnolia.dam.setup.MigrateContentFromDMSToDAMTask.convertContentNodesToDAM(MigrateContentFromDMSToDAMTask.java:183)
[INFO] [talledLocalContainer] at info.magnolia.dam.setup.MigrateContentFromDMSToDAMTask.doExecute(MigrateContentFromDMSToDAMTask.java:74)
[INFO] [talledLocalContainer] at info.magnolia.module.delta.AbstractRepositoryTask.execute(AbstractRepositoryTask.java:60)

No idea why that enforced child node is sometimes not around.