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1. NiFi and NiFi-registry are two totally different pieces of software. Each of these services are likely running as different service users. HDF service user defaults: NiFi service --- default service user is "nifi"
NiFi Registry service ---> default service user is "nifiregistry"
2. The NiFi service is where you are building your dataflows on the canvas. The NiFi-Registry service is used to store version controlled dataflows from your NiFi.
3. Make sure that the directory you are trying to ingest files is accessible by the nifi service user. Suggest accessing server via command line and becoming the nifi service user (#sudo su - nifi) and then navigate to the target directory cd /home/xxx/receive.
Keep in mind that even though the "receive" directory may be set to 777, if the nifi service user can't access /home or /home/xxx they will not be able to see "/home/xxx/receive" regardless of what permissions are set on that directory.