File Transfers Intermittently Hang in Spark

Running Openfire 3.8.1 and Spark 2.6.3

When trying to transfer files to other in-network users on the same subdomain, file transfers hang at less than 30% about two thirds of the time. Sometimes after multiple attempts the same file will go through, other times it does not. Some users are not experiencing problems at all. I do not see any logs that seem to indicate the issue, but honestly I am not quite sure what to look for. No error message appears in Spark. Have tested this on my machine with Windows firewall disabled, port 7777 is not open on external firewall, but this was working well at first and no changes were made.

It seems to go down in frequency after restarting the server, but we have users on 24/7, I’d rather not have to restart the server every night, and would rather fix the issue permanantly.

Any ideas on this? Even an idea where to start looking would be helpful. Thank you!

Just started using that same combination and am seeing the same issue.

The Spark log shows:

SEVERE: Error occured during file transfer.

error writing to output stream:

– caused by: java.io.IOException: Error while sending Data: No response from server.

at org.jivesoftware.smackx.filetransfer.FileTransfer.writeToStream(FileTransfer.ja va:219)

at org.jivesoftware.smackx.filetransfer.OutgoingFileTransfer$2.run(OutgoingFileTra nsfer.java:231)

at java.lang.Thread.run(Unknown Source)

plus more error messages.

It seems like the client isn’t persistent enough, or times out too quickly, or doesn’t retry. Why the error even occurs I can’t really tell, some sort of extreme sensitivity to internet imperfection. I see the same client going offline then immediately online many times throughout the day. Again, it seems like some sort of internet issue to which Spark is way too sensistive. Maybe the connection has slow ping times or poor ttl, but somehow the client needs to be more robust.