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When opening an Office document from a SharePoint 2016 on-prem server, Office gets stuck on saving changes back to the server. Often a status of "Uploading to SharePoint" is continually shown or "Updating Workflow Status" is continually displayed at the bottom of Word. When we disabled our forward proxy settings, the behavior goes away. When we check our forward proxy logs though, no traffic appears to be blocked. In fact, our intranet is whitelisted on our forward proxy. We tried to use Fiddler to see what requests were being made, but the save process works whenever we have Fiddler decrypt the HTTPS traffic. We suspect it might be related to some kind of cert issue, but uncertain how to get enough diagnostic info from the Office client to troubleshoot further. Also, sometimes if we disable the forward proxy, open a document from SharePoint, and then save it back successfully, we can then turn the forward proxy back on and still open and save that document. However, if we wait a day, the issue returns for that document.
We did find the ultimate cause of this nasty thorn in our side. We use Web Application Firewall (WAF) devices and there was an obscure setting deep in the advanced config related to traffic management. The setting was "Request Buffer Size Limit (KB)". It was set too low for some of the authentication requests related to SharePoint/Office. We increased it to 32KB and the issues dissappeared. Drove us crazy for months. You can't even see the setting unless you turn another another "Show Advanced Settings". That's saying something consideration the thousands of settings that are shown before toggling the advanced options :) Hope this helps someone avoid the pain we endured ;)
Thanks for this tip. We are also (mis)using a software firewall. We adjusted Request Buffer size but it did not stop our issue. (We were seeing some blockages due to request size, to it seemed to eliminate those, but we had to bump it to 10MB or something) We are using FortiWeb and I have discovered it attaches a cookie called "cookiesession1" to requests sent from MS Word to SharePoint. Normally this is not an issue, but once in a while it attaches a second cookie with the same name and this seems to cause issues. My theory is that FortiWeb itself is invalidating sessions when it sees two cookies, maybe some kind of defence mechanism. My next step is to convince my system administrator to disable this cookie and see whether that resolves our issue.
UPDATE: turning off session cookies did not resolve our issue. For the time being our only course of action is to bypass the software firewall.
Hi, @SJNBham ,
According to your description, it seems that the office and SharePoint 2016 works fine and the issue only occurs when the forward proxy is enabled. As it is a network issue now, it is more related to the proxy server provider instead of SharePoint. This is beyond the scope of this forum and I am afraid I will not be able to provide much help about this. It will be better to contact the team who provide the forward proxy service and have a check on their side.
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@Jerry Xu-MSFT - Thanks for your reply. We posted the question in this forum in hopes others might have experienced this issue and found the root cause. As mentioned in the original post, our forward proxy isn't logging any denied requests. Also, there's no issue editing and saving docs in O365. The O365 traffic is going through the same forward proxy. It's possible there's something specific to our SharePoint Server config contributing to the issue - even though it seems disabling the forward proxy "resolves" the issue.
Is there an update on this issue? We are encountering the exact same behavior, including the "Fiddler fix". I don't know if we have forward proxy, but we definitely have irate users.