'Error 0' when uploading file to Alfresco - only one user affected
I have a user who previously could upload files to Alfresco Community 5.0.2 but now cannot, even when trying different browsers (e.g. Chrome, FireFox). Other users seem fine, and I also cannot reproduce the issue even if I sign on with his account on another machine (with his permission, of course).
During his uploads it sometimes says 20% or 70% uploaded (even for the same file), but eventually he gets an "Error 0" popup message (I'll upload a screenshot shortly, if I can). This occurs for all files, regardless of size/name/filetype/etc. And, there is nothing I can see in the server logs. Actually, we're running Alfresco behind an Apache reverse proxy, and I see zero traffic to Apache when he tries to upload (by inspecting apache.logs), so I think his browser is failing to contact the server after his drag-and-drop to start the upload.
Please let me know any ideas or any logs I can capture/check to maybe narrow this down. Currently, I think it's not a server side issue, but I'm not familar at all with browser-side debugging and currently feeling very stuck at the moment.
Thanks very much for any help or ideas you can share!
Also, an update. I found a workaround for the user. Our Alfresco server can be reached via two IP addresses, and I asked him to switch to the one I'm using and he can upload now. I'm not sure yet what the issue is with using the other IP address, but it seems to put another proxy server in the path to the Alfresco server. Maybe there's a config issue there, not sure yet.
Either way, thanks all for being available for this question. For root cause study, if you have any advice/links/etc. on configuring Alfresco behind a proxy server, please let me know. I'll start studying this myself as well.