Office Web Apps Not Supported on Non-System Drive



I ran into the following scenario during a recent project.

Skype for Business users were unable to present Power Point Presentations, and were presented with the following error message:

Either you’ve lost network connectivity or our server is too busy to handle your request. Please check your network connection and try again later




As you watched the attempt to share the PPT, you could see that the presentation was successfully uploaded to the meeting. You could see the PPT as an attachment within the “Manage Content” section of the meeting, but after a minute  or two of waiting, users would see the above error displayed in their client. 

Snooper Traces revealed the following:

54020;reason="The WAC presentation failed with a critical error."

ErrorMessage="Either you’ve lost network connectivity or our server is too busy to handle your request. Please check your network connection and try again later."

ULS Logs revealed the following:

AsyncResult::SetCompleted – Completed with unthrown exception Microsoft.Office.Server.Powerpoint.Pipe.Interface.PipeApplicationException: Exception of type ‘Microsoft.Office.Server.Powerpoint.Pipe.Interface.PipeApplicationException’ was thrown.   

at Microsoft.Office.Server.Powerpoint.Pipe.Web.WacViewServices.EndGetItem(IAsyncResult asyncResult)   

at Microsoft.Office.Server.Powerpoint.Pipe.Interface.ResourceRequest.End(IAsyncResult asyncResult)   

at Microsoft.Office.Server.Powerpoint.Pipe.Interface.PipeManager.OnRequestComplete(IAsyncResult result)  WacItemRetrievalResultErrorInfo; ItemRetrivalStatus: InProgress; ErrorCode: ErrorInProgress;


The frustrating part, is that this was all working for several months, and then suddenly stopped working.  The first reports of issues correlated to reboots caused by monthly Windows OS patching.

After spending many hours troubleshooting OWAS, reviewing/uninstalling/reinstalling updates, uninstalling/reinstalling OWAS, digging through Snooper traces, tracing CorrelationId’s in Fiddler to ULS logs, etc…it seems we had finally stumbled upon the answer.



Installing OWAS on a Non-System Drive, in this case (D:\), resulted in the errors above.  While installing OWAS on the System Drive (C:\), resulted in PowerPoints being presenting as expected.

Following up with Microsoft, they said they have had other reports of OWAS being deployed on Non-System drives, and that doing so is UNSUPPORTED

Here is the link they referenced as documentation for it being unsupported…


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