Misuse and misconceptions
When you try to open documents on a SharePoint website, you may receive various error messages, such as, "Sorry we can't open https://" or "Upload failed."
When you search for solutions to this issue on the Internet, you find that a common troubleshooting technique is to add the FSSHTTPOff registry key to the following location, and then set its DWORD value to 1:
In fact, the FSSHTTPOff registry key should never be used as a solution. Adding this registry key prevents Office from using its preferred protocol, and it prevents features that rely on FSSHTTPOff from being used in Office. More importantly, the registry key masks the real problem that affects Office.
We recommend that you scope your issue to key technology areas by using the following guidelines.
Notes: This article applies to the following:
Office Pro Plus Subscription AL
Office Professional Academic 2019
Office Professional Plus 2010 Home Use Program
Office Professional Plus 2019
Office ProPlus 2013
Microsoft 365 Apps for enterprise
What FSSHTTPOff does
Office typically exchanges information with SharePoint through the MS-FSSHTTP protocol. This protocol is commonly known as SOAP. For more information, see [MS-FSSHTTP]: File Synchronization via SOAP over HTTP Protocol.
Office features, such as co-authoring, checking documents in and out, reverting to earlier versions of documents, filling out required file properties, and so on, rely on this protocol to be able to function.
The endpoint that SharePoint uses to exchange information over this protocol is the CellStorage web service. This service name and functionality are consistent on any supported SharePoint on-premises farm and on any SharePoint Online tenant.
Before SOAP was developed, Office used the WebDAV protocol to exchange information with SharePoint. WebDAV enables Office only to do basic things with SharePoint documents.
Using the FSSHTTPOff registry key completely prevents Office from using the SOAP protocol and all its associated features, and forces Office to use WebDAV instead.
How to use FSSHTTPOff correctly
Before you consider using this registry key, we strongly recommend that you narrow the investigation of your issue to one of the following technology areas because they are all potential failure points.
Is Office up-to-date?
Do all security and feature updates apply to Office (MSI)?
Do all channels of Office (C2R) reproduce?
Are mixed Office versions running on the computer?
For example, Office 2013 MSI and Office 2013 Click-to-Run are installed on the same computer.
Does clearing the Office file cache help?
Does this issue reproduce on all web applications?
Does this issue reproduce on all site collections?
Does this issue reproduce on both production and test farms (on-premises)?
Does this issue reproduce on multiple tenants (online)?
Does this issue reproduce on all sites?
Does this issue reproduce on all libraries?
Does this issue reproduce on all files?
Does this issue reproduce on only Office files or all files?
Does this issue reproduce on newly created files?
Do all users experience this issue?
Can a nonworking user sign in to a working user's computer and reproduce this issue?
Can a working user sign in to a nonworking user's computer and reproduce this issue?
Are you able to test whether your issue occurs through a virtual private network (VPN) outside your corporate network from home or a coffee shop?
Are there any proxies, firewalls, traffic shapers or WAN accelerators that may be a factor?
Narrowing the issue
If you've narrowed the issue by using these guidelines, testing the registry key makes sense in the context of the situation.
There is value in troubleshooting by using this registry key, because both positive and negative results can help point you in certain directions.
If the negative behavior stops when you add the key, it may mean the following:
Office is in a bad state, or the Office file cache has to be cleared.
Problems that are affecting Office are occurring on a SharePoint site that uses the CellStorage service.
If the negative behavior doesn't stop when you add the registry key, this may mean the following:
A networking issue is preventing Office from communicating with SharePoint.
Applications that are external to Office or external to the computer don't let Office communicate with SharePoint freely.