"is already marked for transfer" in PutDatabaseRecord after merging JSON objects

[#1]

I have the following Nifi Flow:

QueryDatabaseTable -> AvroToJSON -> SplitJSON -> ExtractText (write value to attribute) -> FetchDistributedMapCache (check if the attribute is available in cache, which is set in another flow) -> UpdateRecord (Rename some fields) -> MergeContent -> PutDatabaseRecord

And sometimes this error occurs:

The FlowFile is not routed to failure, but kept in the queue and the Processor is now stuck in an endless loop trying to process the faulty FlowFile.

When i skip the MergeContent/MergeRecord Processor and just write to the database for each record this error does not occurr, but writing for each object is very slow.

Why does this happen? How can I debug this?

[#2]

Hi, I hope you have find out what was going on... by the way, I have same problem with flowfiles not going to failure in putHiveQl and putHDFS, they just stuck and dont go to failure.

Do you/someone have any ideia why is this happening?

Tks a lot!

[#3]

Is there anything in the logs before/after the "already marked for transfer" entry? Trying to figure out how a flow file can get transferred and then something goes wrong (where we'd try to also send it to failure)