Sporadic failure to save files: "Failed to retrieve resource from..."


Hi everyone. I’ve got an annoying problem with my self-hosted Cloud9 single-user deployment. When I try to save a file to disk it sporadically fails to save and gives the following error:

Failed to write 'file.py'. Failed to retrieve resource from with code 0.

When this happens I generally can’t save at all for about a minute, after which it starts working again. It happens several times an hour and seems to happen most often if I’ve been inactive on the C9 tab for a few minutes. Any idea what’s wrong and how to fix it? Thanks!