JOSM: IO Exception - unable to upload data

I have received the following message three times recently in JOSM 9329 when attempting to upload my edits:
IO Exception
“Failure to upload data or to download data from ‘’ due to a problem with transferring data. Details (untranslated): Stream closed”
I saved my current data to a .osm file on each occasion and was able to upload the edits later. This has never happened to me before these three events. I have been able to upload data subsequently so far by powering off my computer and restarting it but I am disturbed by the message’s sudden appearance.

Crossposting with

Does the solution help there?

I tried the suggestion as I understood it but it had no effect. As I began, the one solution so far is to restart my PC but this is rather inconvenient. I plan to uncheck a couple of recent plug-ins and use JOSM version 9229 to determine whether either action makes any difference.
I thank you for you interest.