Hi @qqilihq,
This second error you’ve been posting looks like an unrelated issue that has recently been brought to our attention via our automated tests. It could occur in the rare case when a table was cleared / discarded exactly at the moment when it was just finished being written to disk by some asynchronous process. The reason why you are seeing this in a loop is that here tables are frequently cleared shortly after they have been created / written to disk. It has since been fixed on our nightly build, but not (yet) in any of our released products. Apologies!
I have created a ticket for the first issue you (and @gcincilla) have reported. It is certainly odd that the workflow temp directory is deleted while the workflow is running. The only point in time where I know KNIME AP would delete this directory is when the workflow is closed. As mentioned earlier, what I could also see being the case is that the OS deletes that temp folder since it has not been modified for an extended period of time (e.g., due to KNIME AP being stuck in a long-running loop during which it processes only small tables that are not flushed to the temp folder). Having said that, we will investigate more thoroughly and check if there are any other occasions where KNIME could accidentally delete that folder (for whatever reason).
Regards,
Marc