WebDAV - Microsoft Excel 2016 not able to save back changes

Question

I have a set up the ITHit WebDAV server on our company website which works great on Office 2007/10/13 with PowerPoint, Word and Excel. However I have recently updated to Office 2016 and I have found that Excel no longer works, however Word and PowerPoint work OK.

In Excel I get the error message below:

In Word and PowerPoint I get the dialog below which I can skip:

Is there a known issue with the ITHit WebDAV server in Excel 2016?

There are no exceptions thrown when I'm attached in Visual Studio 2015. Also when I've checked Fiddler I can see the last thing the WebDAV server try to do is lock the document which is seems to do without any exceptions. It locked and unlocks the document twice then on the lock where I try to save it then comes back with the error message in Excel (see pic 1).

The lock requests are shown below:

First Lock OK:

Unlock:

locks the document and stops:

The only think I can see that is different is a field in the Miscellaneous section of the header:

I've exhausted all options and I've got no idea why this is happening with just excel in office 2016.

Any help would be greatly appreciated.

You may have better luck on superuser, one of SO's sister sites. — Brian Warshaw
Apologies I didn't mention this in the post, this is C# programming issue, specifically with the ITHit WebDAV Server library. Superuser look like its targeted to network admins and the like? — Weggo
If you are trying to troubleshoot issues that won't be resolved by you writing code, then SO isn't the place. And so if you're asking the question "Is there a known issue with the ITHit WebDAV server in Excel 2016?", that seems like a better fit for Superuser, which is where you'd go for general-purpose computing help. If you wrote the webserver, or if something you're coding is what's (potentially broken), then this is the right place, but you may want to make your question clearer, as it currently appears to be asking about compatibility issues in existing software. — Brian Warshaw
Thank for your reply, I will also post a comment on there. I was advised by IT Hit, the developers of this product to post all questions here. — Weggo
The server is a c# library that helps you implement WebDAV based on your own custom storage. Fixes would most likely involve returning different statuses from code, so I think this is a good place to post it. I do wish that ITHit had their own (active) support forums though. — LouD

LouD LouD · Accepted Answer · 2016-11-09T16:39:27

This error has been around for a while and I found an old related Microsoft post:

http://answers.microsoft.com/en-us/msoffice/forum/msoffice_excel-mso_other/upload-failed-server-file-updated-were-sorry/30b69218-2cc1-40e2-8ede-69ac8bd55ba6

Microsoft never came up with a solution, but a user named Berend Engelbrecht did post two workarounds. There was a code fix which did not work for me, but is worth trying. The assumption was that Excel incorrectly handled the modified date so don't bother returning it. This is how I implemented it for IT Hit WebDAV. Setting Modified to DateTime.MinValue in my implementation of IHierarchyItemAsync prevented the modified date from being added to the response.

if (context.Request.UserAgent != null &&
    context.Request.UserAgent.IndexOf("Microsoft Office Excel", StringComparison.InvariantCultureIgnoreCase) >= 0)
{
    Modified = DateTime.MinValue;
}

The second solution did work, but was not practical for our end users. Each would have to turn off Protected View for internet files: File > Options > Trust Center > Trust Center Settings > Protected View.

Also note that when debugging locally, I never hit the issue because my local WebDAV didn't trigger Protected View as an 'internet location'.

Hope one of these helps and if anyone finds a different solution please post it here.

WebDAV - Microsoft Excel 2016 not able to save back changes

3 Answers