How to recover from "Proposed Flow does not contain a Connection with ID xxx but this instance has data queued in that connection"?

One of my nifi nodes/instances is refusing to reconnect to the cluster

Proposed flow is not inheritable by the flow controller and cannot completely replace the current flow due to: Proposed Flow does not contain a Connection with ID 4d2c4e9d-0176-1000-0000-0000310c611f but this instance has data queued in that connection, updateId=307]

Without entering in why this happened, how can I recover from this error? Even if I overwrite the flow.xml.gz file it will refuse to accept it because it knows that there is data queued for that connection.

Can I flush / delete that data somehow?

I had tried to delete/move

flow.xml.gz
flowfile_repository
content_repository
database_repository

But I get the same error on startup, where does Nifi track that connection 4d2c4e9d-0176-1000-0000-0000310c611f had data in this nifi node?

Solution

Deleting (back it up first) the flow.xml.gz file should fix it.

Make sure that you are actually moving/deleting the right flox.xml.gz file since it may not be in the default location.

So check the actual location of the flow file at $NIFI_HOME/conf/nifi.properties , look for nifi.flow.configuration.file. Then delete that one (backup first) and the node should be able to reconnect.